An original Thinka practice paper modelled on the structure and difficulty of the Nov 2024 (V2) Cambridge International A Level Mathematics (0580) paper. Not affiliated with or reproduced from Cambridge.
Paper 12 (Core)
Answer all questions. Use of a calculator is permitted where appropriate. Show all necessary working clearly.
22 Question · 55 marks
Question 1 · short_answer
2.5 marks
Solve the equation \(4(3x - 5) = 2x + 15\).
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Worked solution
Expand the brackets: \(12x - 20 = 2x + 15\). Subtract \(2x\) from both sides: \(10x - 20 = 15\). Add 20 to both sides: \(10x = 35\). Divide by 10: \(x = 3.5\).
Marking scheme
M1 for correct expansion of the bracket: \(12x - 20\). M1 for collecting like terms: \(10x = 35\) (or equivalent). A1 for \(x = 3.5\) (or \(\frac{7}{2}\)).
Question 2 · short_answer
2.5 marks
Work out \(2\frac{3}{4} \div \frac{7}{8}\). Give your answer as a mixed number in its simplest form.
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Worked solution
Convert the mixed number to an improper fraction: \(2\frac{3}{4} = \frac{11}{4}\). To divide by \(\frac{7}{8}\), multiply by its reciprocal: \(\frac{11}{4} \times \frac{8}{7} = \frac{88}{28}\). Simplify the fraction: \(\frac{88}{28} = \frac{22}{7}\). Convert back to a mixed number: \(\frac{22}{7} = 3\frac{1}{7}\).
Marking scheme
M1 for converting to \(\frac{11}{4} \times \frac{8}{7}\) or \(\frac{22}{7}\). A1 for \(3\frac{1}{7}\) (accept \(\frac{22}{7}\) for 1.5 marks if mixed number format is omitted).
Question 3 · short_answer
2.5 marks
Two parallel lines are intersected by a straight line. A pair of alternate angles are represented by \((3x - 10)^\circ\) and \((2x + 30)^\circ\). Find the value of \(x\).
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Worked solution
Since alternate angles are equal, set the two expressions equal to each other: \(3x - 10 = 2x + 30\). Subtract \(2x\) from both sides: \(x - 10 = 30\). Add 10 to both sides: \(x = 40\).
Marking scheme
M1 for setting up the equation \(3x - 10 = 2x + 30\). A1 for \(x = 40\).
Question 4 · short_answer
2.5 marks
A cylindrical container has a radius of \(6\text{ cm}\) and a height of \(15\text{ cm}\). Calculate the volume of the container. Give your answer correct to 1 decimal place.
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Worked solution
Use the formula for the volume of a cylinder: \(V = \pi r^2 h\). Substitute \(r = 6\) and \(h = 15\): \(V = \pi \times 6^2 \times 15 = 540\pi\). Calculate the numerical value: \(V \approx 1696.46\text{ cm}^3\). Rounding to 1 decimal place gives \(1696.5\text{ cm}^3\).
Marking scheme
M1 for \(\pi \times 6^2 \times 15\). A1 for \(1696.5\) (accept \(1696.46\) to \(1696.5\)).
Question 5 · short_answer
2.5 marks
Ayla invests \(\$4800\) at a rate of \(2.5\%\) per year simple interest. Calculate the total value of her investment at the end of \(4\) years.
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Worked solution
Calculate the simple interest earned using the formula \(I = \frac{P \times R \times T}{100}\): \(I = \frac{4800 \times 2.5 \times 4}{100} = 480\). Calculate the total value by adding the interest to the principal amount: \(\text{Total Value} = 4800 + 480 = 5280\).
Marking scheme
M1 for correct substitution into simple interest formula: \(\frac{4800 \times 2.5 \times 4}{100}\). A1 for finding the interest as \(480\) (or total value \(5280\)).
Question 6 · short_answer
2.5 marks
A curve has the equation \(y = x^2 - 4x - 5\). Find the coordinates of the minimum point of this curve.
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Worked solution
The x-coordinate of the minimum point of a quadratic curve \(y = ax^2 + bx + c\) is given by \(x = -\frac{b}{2a}\). Substitute \(a = 1\) and \(b = -4\): \(x = -\frac{-4}{2(1)} = 2\). Now, substitute \(x = 2\) into the original equation to find the y-coordinate: \(y = 2^2 - 4(2) - 5 = -9\). Thus, the coordinates of the minimum point are \((2, -9)\).
Marking scheme
M1 for finding \(x = 2\) (using axis of symmetry or completing the square). A1 for \((2, -9)\).
Question 7 · short_answer
2.5 marks
A rectangular field has a length of \(24\text{ m}\) and a width of \(10\text{ m}\). Calculate the length of the diagonal of the field.
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Worked solution
The diagonal of a rectangle forms a right-angled triangle with the length and width as the legs. Use Pythagoras' Theorem: \(d^2 = 24^2 + 10^2 = 576 + 100 = 676\). Thus, \(d = \sqrt{676} = 26\text{ m}\).
Marking scheme
M1 for \(24^2 + 10^2\). A1 for \(26\).
Question 8 · short_answer
2.5 marks
The angles of a triangle are in the ratio \(3 : 4 : 5\). Calculate the size of the smallest angle of this triangle.
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Worked solution
The sum of the angles in a triangle is \(180^\circ\). Find the total number of parts in the ratio: \(3 + 4 + 5 = 12\text{ parts}\). The smallest angle corresponds to the part with the value 3: \(\text{Smallest angle} = \frac{3}{12} \times 180^\circ = 45^\circ\).
Marking scheme
M1 for \(\frac{3}{12} \times 180\) (or finding 1 part = \(15^\circ\)). A1 for \(45\).
Question 9 · short_answer
2.5 marks
Solve the equation \(3(2x - 5) = 4x + 7\).
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Worked solution
Expand the bracket first: \(6x - 15 = 4x + 7\). Next, subtract \(4x\) from both sides: \(2x - 15 = 7\). Add 15 to both sides: \(2x = 22\). Finally, divide by 2: \(x = 11\).
Marking scheme
M1 for expanding the bracket to get \(6x - 15\). M1 for isolating the \(x\) terms and constant terms (e.g., \(2x = 22\)). A0.5 for the final correct answer 11.
Question 10 · short_answer
2.5 marks
A curve has the equation \(y = 2x^2 - 3x + 1\). Find the value of \(y\) when \(x = -3\).
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Worked solution
Substitute \(x = -3\) into the equation: \(y = 2(-3)^2 - 3(-3) + 1\). Evaluate the powers and multiplications: \(y = 2(9) + 9 + 1 = 18 + 9 + 1\). Add the numbers together to get: \(y = 28\).
Marking scheme
M1 for substituting \(x = -3\) into the expression with at most one sign error. M1 for simplifying the terms to \(18 + 9 + 1\). A0.5 for the final answer 28.
Question 11 · short_answer
2.5 marks
An isosceles triangle \(ABC\) has sides \(AB = AC = 13\text{ cm}\) and base \(BC = 10\text{ cm}\). Calculate the perpendicular height of the triangle from \(A\) to the base \(BC\).
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Worked solution
Let \(D\) be the midpoint of the base \(BC\). Since the triangle is isosceles, the perpendicular line from \(A\) to \(BC\) bisects the base, so \(BD = 5\text{ cm}\). In the right-angled triangle \(ABD\), use Pythagoras' theorem: \(AD^2 + BD^2 = AB^2\), which gives \(AD^2 + 5^2 = 13^2\). This simplifies to \(AD^2 + 25 = 169\), so \(AD^2 = 144\). Taking the square root gives \(AD = 12\text{ cm}\).
Marking scheme
M1 for identifying the half-base length of \(5\text{ cm}\). M1 for setting up the Pythagoras equation: \(h^2 + 5^2 = 13^2\) or \(h = \sqrt{13^2 - 5^2}\). A0.5 for the final correct answer 12.
Question 12 · short_answer
2.5 marks
A prism has a cross-section in the shape of a right-angled triangle with base \(6\text{ cm}\) and height \(8\text{ cm}\). The length of the prism is \(15\text{ cm}\). Calculate the volume of the prism.
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Worked solution
First, calculate the area of the triangular cross-section: \(\text{Area} = \frac{1}{2} \times \text{base} \times \text{height} = \frac{1}{2} \times 6 \times 8 = 24\text{ cm}^2\). Then, calculate the volume by multiplying this cross-sectional area by the length of the prism: \(\text{Volume} = 24 \times 15 = 360\text{ cm}^3\).
Marking scheme
M1 for finding the area of the triangular cross-section: \(\frac{1}{2} \times 6 \times 8\). M1 for multiplying their cross-sectional area by \(15\). A0.5 for the final answer 360.
Question 13 · short_answer
2.5 marks
In a school of 120 students, 45 students play football, 33 play basketball, and the rest play tennis. What percentage of the students play tennis?
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Worked solution
First, find the number of students who play tennis: \(120 - 45 - 33 = 42\text{ students}\). Next, calculate this as a percentage of the total student population: \(\frac{42}{120} \times 100\% = 0.35 \times 100\% = 35\%\).
Marking scheme
M1 for finding the number of tennis players: \(120 - 45 - 33 = 42\). M1 for writing the correct fraction multiplied by 100: \(\frac{42}{120} \times 100\). A0.5 for the final answer 35.
Question 14 · short_answer
2.5 marks
The exterior angle of a regular polygon is \(40^\circ\). Calculate the number of sides of this polygon.
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Worked solution
The sum of the exterior angles of any regular convex polygon is \(360^\circ\). Let \(n\) represent the number of sides. Since each exterior angle is \(40^\circ\), we have: \(n = \frac{360^\circ}{40^\circ} = 9\).
Marking scheme
M1.5 for setting up the division \(\frac{360}{40}\) or the equation \(40 \times n = 360\). A1 for the correct answer 9.
Question 15 · short_answer
2.5 marks
A shopkeeper buys a bicycle for $160 and sells it for $208. Calculate the percentage profit.
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Worked solution
First, calculate the actual profit made: \(\text{Profit} = 208 - 160 = 48\). Then, find the percentage profit relative to the original cost price: \(\text{Percentage Profit} = \frac{48}{160} \times 100\% = 0.3 \times 100\% = 30\%\).
Marking scheme
M1 for finding the profit: \(208 - 160 = 48\) (or for working out the scale factor: \(\frac{208}{160} \times 100 = 130\%\)). M1 for calculating the fraction \(\frac{48}{160} \times 100\) (or \(130 - 100\)). A0.5 for the correct answer 30.
Question 16 · short_answer
2.5 marks
Solve the simultaneous equations. \(3x + 2y = 17\) \(4x - y = 19\)
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Worked solution
Multiply the second equation by 2 to align the coefficients of \(y\): \(8x - 2y = 38\). Now add this new equation to the first equation: \((3x + 2y) + (8x - 2y) = 17 + 38\), which simplifies to \(11x = 55\), giving \(x = 5\). Substitute \(x = 5\) into the second equation: \(4(5) - y = 19\), which gives \(20 - y = 19\), so \(y = 1\).
Marking scheme
M1 for a valid method to eliminate one variable (e.g., multiplying the second equation by 2 and adding to the first). M1 for finding one correct variable value (\(x = 5\) or \(y = 1\)). A0.5 for both correct values: \(x = 5, y = 1\).
Question 17 · short_answer
2.5 marks
Solve the equation: \(\frac{3x - 5}{4} = 7\)
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Worked solution
First, multiply both sides of the equation by 4 to get \(3x - 5 = 28\). Next, add 5 to both sides of the equation to get \(3x = 33\). Finally, divide both sides by 3 to get \(x = 11\).
Marking scheme
M1 for multiplying both sides by 4 to get \(3x - 5 = 28\). M1 for adding 5 to both sides to get \(3x = 33\). A0.5 for the correct answer 11.
Question 18 · short_answer
2.5 marks
Calculate the volume of a cylinder with a radius of \(4\text{ cm}\) and a height of \(10\text{ cm}\). Give your answer correct to 1 decimal place.
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Worked solution
Use the formula for the volume of a cylinder, \(V = \pi r^2 h\). Substitute \(r = 4\) and \(h = 10\): \(V = \pi \times 4^2 \times 10 = 160\pi\). Evaluating this gives \(V \approx 502.6548\text{ cm}^3\). Rounding to 1 decimal place gives \(502.7\text{ cm}^3\).
Marking scheme
M1 for substituting values into correct volume formula: \(\pi \times 4^2 \times 10\). M1 for \(160\pi\) or \(502.65...\). A0.5 for correct answer of 502.7.
Question 19 · short_answer
2.5 marks
A regular polygon has an exterior angle of \(40^\circ\). Calculate the number of sides of this polygon.
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Worked solution
The sum of the exterior angles of any convex polygon is \(360^\circ\). For a regular polygon with \(n\) sides, each exterior angle is \(\frac{360^\circ}{n}\). Thus, \(\frac{360}{n} = 40\), which gives \(n = \frac{360}{40} = 9\).
Marking scheme
M1 for setting up the equation \(\frac{360}{n} = 40\) or showing \(360 \div 40\). A1.5 for the correct answer 9.
Question 20 · short_answer
2.5 marks
A laptop is on sale with a \(15\%\) discount. The original price of the laptop was \(\$640\). Calculate the sale price of the laptop.
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Worked solution
The discount amount is \(15\%\) of \(\$640\), which is \(0.15 \times 640 = 96\). The sale price is the original price minus the discount: \(640 - 96 = 544\). Alternatively, calculate \(85\%\) of \(\$640\): \(640 \times 0.85 = 544\).
Marking scheme
M1 for calculating the discount as \(96\) or identifying the multiplier \(0.85\). M1 for subtracting the discount from the original price or evaluating \(640 \times 0.85\). A0.5 for the correct answer 544.
Question 21 · short_answer
2.5 marks
Calculate the area of a triangle with side lengths \(8\text{ cm}\) and \(12\text{ cm}\), and an included angle of \(30^\circ\).
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Worked solution
Use the formula for the area of a triangle: \(\text{Area} = \frac{1}{2} a b \sin(C)\). Substituting the given values: \(\text{Area} = \frac{1}{2} \times 8 \times 12 \times \sin(30^\circ)\). Since \(\sin(30^\circ) = 0.5\), this simplifies to \(\text{Area} = 48 \times 0.5 = 24\text{ cm}^2\).
Marking scheme
M1 for substituting into the formula: \(\frac{1}{2} \times 8 \times 12 \times \sin(30^\circ)\). M1 for evaluating \(\sin(30^\circ) = 0.5\) or showing \(48 \times \sin(30^\circ)\). A0.5 for the correct area of 24.
Question 22 · short_answer
2.5 marks
A curve has the equation \(y = 2x^2 - 5x + 1\). Find the value of \(y\) when \(x = -3\).
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Worked solution
Substitute \(x = -3\) into the equation: \(y = 2(-3)^2 - 5(-3) + 1\). Evaluate each term: \(2(-3)^2 = 2 \times 9 = 18\) and \(-5(-3) = 15\). Summing these terms with 1: \(y = 18 + 15 + 1 = 34\).
Marking scheme
M1 for substituting \(x = -3\) correctly into the expression: \(2(-3)^2 - 5(-3) + 1\). M1 for dealing with signs to get \(18 + 15 + 1\). A0.5 for correct answer of 34.
Paper 22 (Extended)
Answer all questions. Use of a calculator is permitted where appropriate. Show all necessary working clearly.
23 Question · 69 marks
Question 1 · short_answer
3 marks
Solve the equation. \[\frac{6}{x-1} - \frac{4}{x} = 1\]
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Worked solution
We multiply both sides of the equation by the common denominator \(x(x-1)\): \[6x - 4(x-1) = x(x-1)\]
This gives the solutions: \[x = 4 \quad \text{or} \quad x = -1\]
Marking scheme
- M1 for eliminating the fractions correctly: \(6x - 4(x-1) = x(x-1)\) or equivalent - M1 for rearranging into standard quadratic form: \(x^2 - 3x - 4 = 0\) - A1 for both answers \(4\) and \(-1\)
Question 2 · short_answer
3 marks
Find the coordinates of the turning point of the curve \(y = 3x^2 - 12x + 7\).
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Worked solution
**Method 1: Completing the square** We write the quadratic in vertex form: \[y = 3(x^2 - 4x) + 7\] \[y = 3\left[(x - 2)^2 - 4\right] + 7\] \[y = 3(x - 2)^2 - 12 + 7\] \[y = 3(x - 2)^2 - 5\] The coordinates of the turning point are \((2, -5)\).
**Method 2: Calculus** Find the derivative of \(y\) with respect to \(x\): \[\frac{\mathrm{d}y}{\mathrm{d}x} = 6x - 12\] Set the derivative equal to \(0\) to find the \(x\)-coordinate of the turning point: \[6x - 12 = 0 \implies x = 2\] Substitute \(x = 2\) back into the original equation to find the \(y\)-coordinate: \[y = 3(2)^2 - 12(2) + 7 = 12 - 24 + 7 = -5\] So, the turning point is \((2, -5)\).
Marking scheme
- M1 for an attempt to complete the square or finding the derivative: \(\frac{\mathrm{d}y}{\mathrm{d}x} = 6x - 12\) - A1 for finding the correct \(x\)-coordinate: \(x = 2\) (or one coordinate correct in the turning point) - A1 for the correct coordinates: \((2, -5)\)
Question 3 · short_answer
3 marks
In triangle \(ABC\), \(AB = 7\text{ cm}\), \(BC = 9\text{ cm}\) and angle \(ABC = 112^\circ\). Calculate the length of \(AC\). Give your answer correct to 3 significant figures.
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Worked solution
We use the Cosine Rule to find the length of \(AC\): \[AC^2 = AB^2 + BC^2 - 2(AB)(BC)\cos(\angle ABC)\]
Substitute the given values: \[AC^2 = 7^2 + 9^2 - 2(7)(9)\cos(112^\circ)\] \[AC^2 = 49 + 81 - 126\cos(112^\circ)\]
Rounding to 3 significant figures, we get \(AC = 13.3\text{ cm}\).
Marking scheme
- M1 for correct substitution into the Cosine Rule: \(7^2 + 9^2 - 2(7)(9)\cos(112^\circ)\) - M1 for \(AC^2 \approx 177.2\) (or \(AC = \sqrt{177.2...}\)) - A1 for \(13.3\) (accept \(13.31\))
Question 4 · short_answer
3 marks
A solid metal hemisphere has radius \(r\text{ cm}\). A solid cone of radius \(r\text{ cm}\) and height \(12\text{ cm}\) is melted down and recast, together with the hemisphere, to form a single solid sphere of radius \(2r\text{ cm}\). Find the value of \(r\).
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Worked solution
The volume of a hemisphere is given by: \[V_{\text{hemisphere}} = \frac{2}{3}\pi r^3\]
The volume of a cone is given by: \[V_{\text{cone}} = \frac{1}{3}\pi r^2 h = \frac{1}{3}\pi r^2 (12) = 4\pi r^2\]
The volume of the recast sphere of radius \(2r\) is: \[V_{\text{sphere}} = \frac{4}{3}\pi (2r)^3 = \frac{4}{3}\pi (8r^3) = \frac{32}{3}\pi r^3\]
Since the combined volumes of the hemisphere and the cone equal the volume of the sphere: \[\frac{2}{3}\pi r^3 + 4\pi r^2 = \frac{32}{3}\pi r^3\]
Divide the entire equation by \(\pi r^2\) (since \(r \neq 0\)): \[\frac{2}{3}r + 4 = \frac{32}{3}r\]
Subtract \(\frac{2}{3}r\) from both sides: \[4 = \frac{30}{3}r\] \[4 = 10r\] \[r = 0.4\]
Marking scheme
- M1 for writing a correct equation for the volumes: \(\frac{2}{3}\pi r^3 + \frac{1}{3}\pi r^2 (12) = \frac{4}{3}\pi (2r)^3\) or equivalent - M1 for simplifying to a linear equation in \(r\): \(4 = 10r\) or equivalent - A1 for \(0.4\) or \(\frac{2}{5}\)
Question 5 · short_answer
3 marks
An investment of \(\$P\) grows at a compound interest rate of \(3.5\%\) per year. After 5 years, the value of the investment is \(\$2969.22\), correct to the nearest cent. Find the value of \(P\).
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Worked solution
We use the formula for compound interest: \[A = P\left(1 + \frac{r}{100}\right)^n\]
Substitute the known values into the formula: \[2969.22 = P(1 + 0.035)^5\] \[2969.22 = P(1.035)^5\]
- M1 for setting up the equation: \(P(1.035)^5 = 2969.22\) - M1 for rearranging to make \(P\) the subject: \(P = \frac{2969.22}{1.035^5}\) - A1 for \(2500\)
Question 6 · short_answer
3 marks
The interior angles of a pentagon are \(x^\circ\), \((2x - 15)^\circ\), \((x + 25)^\circ\), \((1.5x + 40)^\circ\) and \(160^\circ\). Find the value of \(x\).
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Worked solution
The sum of the interior angles of a polygon with \(n\) sides is given by: \[\text{Sum} = (n - 2) \times 180^\circ\]
For a pentagon (\(n = 5\)): \[\text{Sum} = (5 - 2) \times 180^\circ = 3 \times 180^\circ = 540^\circ\]
Sum the given angles and set equal to \(540^\circ\): \[x + (2x - 15) + (x + 25) + (1.5x + 40) + 160 = 540\]
- M1 for using the sum of interior angles of a pentagon is \(540^\circ\) - M1 for setting up the simplified equation: \(5.5x + 210 = 540\) or equivalent - A1 for \(60\)
Question 7 · short_answer
3 marks
Solve the equation \(27^{x-1} = 9^{2x-5}\).
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Worked solution
Express both bases \(27\) and \(9\) as powers of \(3\): \[27 = 3^3 \quad \text{and} \quad 9 = 3^2\]
Substitute these into the equation: \[(3^3)^{x-1} = (3^2)^{2x-5}\]
Apply the power of a power index law \((a^m)^n = a^{mn}\): \[3^{3(x-1)} = 3^{2(2x-5)}\]
Since the bases are now identical, we can equate the exponents: \[3(x-1) = 2(2x-5)\]
Expand the brackets: \[3x - 3 = 4x - 10\]
Rearrange to solve for \(x\): \[-3 + 10 = 4x - 3x\] \[x = 7\]
Marking scheme
- M1 for writing both bases as powers of 3: \(3^{3(x-1)} = 3^{2(2x-5)}\) or equivalent - M1 for equating the exponents and setting up the linear equation: \(3(x-1) = 2(2x-5)\) - A1 for \(7\)
Question 8 · short_answer
3 marks
A bag contains \(n\) red balls and 6 blue balls. Two balls are selected at random without replacement. The probability that both balls are blue is \(\frac{1}{3}\). Find the value of \(n\).
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Worked solution
The total number of balls in the bag is \(n + 6\).
The probability of selecting the first blue ball is: \[P(\text{First is Blue}) = \frac{6}{n+6}\]
Since the first ball is not replaced, there are now \(5\) blue balls remaining out of a total of \(n + 5\) balls. The probability of selecting a second blue ball is: \[P(\text{Second is Blue}) = \frac{5}{n+5}\]
We are given that the combined probability of both being blue is \(\frac{1}{3}\): \[\frac{6}{n+6} \times \frac{5}{n+5} = \frac{1}{3}\] \[\frac{30}{(n+6)(n+5)} = \frac{1}{3}\]
Multiply both sides by \(3(n+6)(n+5)\): \[90 = (n+6)(n+5)\] \[90 = n^2 + 11n + 30\]
Rearrange to form a quadratic equation: \[n^2 + 11n - 60 = 0\]
Since the number of red balls \(n\) must be a positive integer, we discard \(n = -15\). Thus, \(n = 4\).
Marking scheme
- M1 for setting up the probability product equation: \(\frac{6}{n+6} \times \frac{5}{n+5} = \frac{1}{3}\) (or equivalent with total \(N\)) - M1 for forming a correct quadratic equation: \(n^2 + 11n - 60 = 0\) (or \(N^2 - N - 90 = 0\)) - A1 for \(4\)
Set each factor to zero to find the solutions: \(2x - 5 = 0 \Rightarrow x = 2.5\) \(x + 1 = 0 \Rightarrow x = -1\)
So, the solutions are \(x = -1\) or \(x = 2.5\).
Marking scheme
M1 for multiplying by the common denominator to get \(3(x - 1) + 2(x + 2) = 2(x + 2)(x - 1)\) or equivalent. M1 for rearranging into a standard three-term quadratic form, \(2x^2 - 3x - 5 = 0\) or equivalent. A1 for both correct solutions: \(x = -1\) and \(x = 2.5\) (or equivalent fractions).
Question 10 · short_answer
3 marks
Find the equation of the tangent to the curve \(y = 2x^3 - 3x^2 - 8\) at the point where \(x = 2\).
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Worked solution
1. Find the \(y\)-coordinate when \(x = 2\): \(y = 2(2)^3 - 3(2)^2 - 8 = 16 - 12 - 8 = -4\) So the point of contact is \((2, -4)\).
2. Find the gradient function by differentiating \(y\): \(\frac{dy}{dx} = 6x^2 - 6x\)
3. Substitute \(x = 2\) to find the gradient of the tangent, \(m\): \(m = 6(2)^2 - 6(2) = 24 - 12 = 12\)
4. Write down the equation of the tangent using \(y - y_1 = m(x - x_1)\): \(y - (-4) = 12(x - 2)\) \(y + 4 = 12x - 24\) \(y = 12x - 28\)
Marking scheme
M1 for finding \(\frac{dy}{dx} = 6x^2 - 6x\) (at least one term correct). M1 for finding the \(y\)-coordinate of \(-4\) and substituting \(x = 2\) into their derivative to find the gradient \(12\). A1 for \(y = 12x - 28\) (or any equivalent form).
Question 11 · short_answer
3 marks
In a triangle \(PQR\), \(PQ = 8.4\text{ cm}\), \(QR = 11.2\text{ cm}\), and angle \(PQR = 108^\circ\). Calculate the length of \(PR\). Give your answer correct to 3 significant figures.
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Worked solution
We can use the Cosine Rule to find the unknown side \(PR\): \(PR^2 = PQ^2 + QR^2 - 2(PQ)(QR)\cos(PQR)\)
Substitute the given values into the formula: \(PR^2 = 8.4^2 + 11.2^2 - 2(8.4)(11.2)\cos(108^\circ)\) \(PR^2 = 70.56 + 125.44 - 188.16\cos(108^\circ)\) \(PR^2 = 196 - 188.16(-0.309017)\) \(PR^2 \approx 196 + 58.1446 = 254.1446\)
Take the square root of both sides: \(PR = \sqrt{254.1446} \approx 15.9419\text{ cm}\)
Rounding to 3 significant figures gives \(15.9\text{ cm}\).
Marking scheme
M1 for correct substitution of values into the Cosine Rule: \(8.4^2 + 11.2^2 - 2(8.4)(11.2)\cos(108^\circ)\). A1 for evaluating \(PR^2 \approx 254\) or \(254.1\dots\). A1 for \(15.9\) (accept \(15.94\dots\)).
Question 12 · short_answer
3 marks
A solid metal cone has a base radius of \(5\text{ cm}\) and a slant height of \(13\text{ cm}\). The cone is melted down and recast into a solid sphere. Calculate the radius of the sphere. [The volume, \(V\), of a sphere with radius \(r\) is \(V = \frac{4}{3}\pi r^3\). The volume, \(V\), of a cone with radius \(r\) and height \(h\) is \(V = \frac{1}{3}\pi r^2 h\).]
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Worked solution
1. Find the perpendicular height, \(h\), of the cone using Pythagoras' theorem: \(h = \sqrt{13^2 - 5^2} = \sqrt{169 - 25} = \sqrt{144} = 12\text{ cm\rm}
2. Calculate the volume of the cone: \)V_{\text{cone}} = \frac{1}{3} \pi (5)^2 (12) = 100\pi\text{ cm}^3\)
3. Set the volume of the sphere equal to the volume of the cone: \(\frac{4}{3} \pi R^3 = 100\pi\) Multiply both sides by \(3\) and divide by \(4\pi\): \(R^3 = 75\)
4. Calculate the radius of the sphere: \(R = \sqrt[3]{75} \approx 4.2172\text{ cm}\)
To 3 significant figures, the radius is \(4.22\text{ cm}\).
Marking scheme
M1 for finding the perpendicular height of the cone, \(h = 12\text{ cm}\), using Pythagoras. M1 for equating the volume of the sphere to the volume of the cone: \(\frac{4}{3}\pi R^3 = \frac{1}{3}\pi (5^2)(12)\) or better. A1 for \(4.22\) (accept \(4.217\dots\)).
Question 13 · short_answer
3 marks
In a sale, the price of a bicycle is reduced by \(15\%\). The sale price is then further reduced by \(10\%\) to a final clearance price of \(\$306\). Calculate the original price of the bicycle before any reductions.
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Worked solution
Let \(P\) be the original price of the bicycle.
After a \(15\%\) reduction, the price is: \(P \times (1 - 0.15) = 0.85P\)
After a further \(10\%\) reduction, the price is: \(0.85P \times (1 - 0.10) = 0.85P \times 0.90 = 0.765P\)
We are given that the final price is \(\$306\): \(0.765P = 306\)
Solve for \(P\): \(P = \frac{306}{0.765} = 400\)
The original price was \(\$400\).
Marking scheme
M1 for expressing the combined reductions as a single decimal multiplier: \(0.85 \times 0.90 = 0.765\) (or finding the intermediate price after the first reduction: \(306 / 0.90 = 340\)). M1 for setting up the division equation: \(306 / 0.765\) (or \(340 / 0.85\)). A1 for \(400\).
Question 14 · short_answer
3 marks
A regular polygon has \(n\) sides. Each interior angle of this polygon is \(140^\circ\) greater than each exterior angle. Find the value of \(n\).
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Worked solution
Let \(i\) be the size of each interior angle and \(e\) be the size of each exterior angle.
We know that the interior and exterior angles of any polygon sum to \(180^\circ\): \(i + e = 180^\circ\)
We are given: \(i = e + 140^\circ\)
Substitute the second equation into the first: \((e + 140^\circ) + e = 180^\circ\) \(2e + 140^\circ = 180^\circ\) \(2e = 40^\circ \Rightarrow e = 20^\circ\)
Since the sum of the exterior angles of any regular polygon is \(360^\circ\): \(n = \frac{360^\circ}{e} = \frac{360^\circ}{20^\circ} = 18\)
The polygon has \(18\) sides.
Marking scheme
M1 for forming an equation using \(i + e = 180\) and the given relation, e.g., \(e + 140 + e = 180\). A1 for finding the exterior angle \(e = 20^\circ\) (or the interior angle \(i = 160^\circ\)). A1 for \(18\).
Question 15 · short_answer
3 marks
Evaluate \(\frac{4.5 \times 10^{-6} + 1.2 \times 10^{-5}}{5.0 \times 10^3}\), giving your answer in standard form.
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Worked solution
1. Express both terms in the numerator with the same power of 10 to add them: \(4.5 \times 10^{-6} = 0.45 \times 10^{-5}\)
2. Add the terms in the numerator: \(0.45 \times 10^{-5} + 1.2 \times 10^{-5} = 1.65 \times 10^{-5}\)
3. Perform the division by the denominator: \(\frac{1.65 \times 10^{-5}}{5.0 \times 10^3} = \left(\frac{1.65}{5.0}\right) \times 10^{-5 - 3} = 0.33 \times 10^{-8}\)
4. Convert the result into standard form: \(0.33 \times 10^{-8} = 3.3 \times 10^{-9}\)
Marking scheme
M1 for adding the numerator correctly to obtain \(1.65 \times 10^{-5}\) (or \(0.0000165\)). M1 for dividing by \(5.0 \times 10^3\) to obtain \(0.33 \times 10^{-8}\) (or \(3.3 \times 10^{k}\) where \(k\) is an integer). A1 for \(3.3 \times 10^{-9}\).
Question 16 · short_answer
3 marks
A car travels from town A to town B, a distance of \(40\text{ km}\), at an average speed of \(80\text{ km/h}\). It then travels from town B to town C, a distance of \(120\text{ km}\), at an average speed of \(60\text{ km/h}\). Calculate the average speed of the car for the entire journey from A to C.
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Worked solution
1. Find the time taken for the first part of the journey (from A to B): \(t_1 = \frac{\text{Distance}}{\text{Speed}} = \frac{40\text{ km}}{80\text{ km/h}} = 0.5\text{ hours}\)
2. Find the time taken for the second part of the journey (from B to C): \(t_2 = \frac{\text{Distance}}{\text{Speed}} = \frac{120\text{ km}}{60\text{ km/h}} = 2.0\text{ hours}\)
3. Calculate the total distance and total time for the entire journey: Total Distance = \(40\text{ km} + 120\text{ km} = 160\text{ km}\) Total Time = \(0.5\text{ hours} + 2.0\text{ hours} = 2.5\text{ hours}\)
4. Calculate the average speed: Average Speed = \frac{\text{Total Distance}}{\text{Total Time}} = \frac{160\text{ km}}{2.5\text{ hours}} = 64\text{ km/h}\)
Marking scheme
M1 for calculating both individual times: \(t_1 = 0.5\text{ hours}\) and \(t_2 = 2.0\text{ hours}\) (or equivalent in minutes). M1 for dividing total distance \(160\text{ km}\) by total time \(2.5\text{ hours}\) (or equivalent in minutes). A1 for \(64\).
Question 17 · short_answer
3 marks
Solve the equation \(\frac{2}{x+3} + \frac{3}{x-1} = 1\).
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Worked solution
Multiply both sides of the equation by the common denominator \((x+3)(x-1)\): \(2(x-1) + 3(x+3) = (x+3)(x-1)\). Expand both sides: \(2x - 2 + 3x + 9 = x^2 + 2x - 3\). Simplify to get: \(5x + 7 = x^2 + 2x - 3\). Rearrange the terms into a quadratic equation: \(x^2 - 3x - 10 = 0\). Factorise the quadratic equation: \((x-5)(x+2) = 0\). This gives the solutions: \(x = 5\) or \(x = -2\).
Marking scheme
M1 for writing with a common denominator, e.g. \(2(x-1) + 3(x+3) = (x+3)(x-1)\) or better. M1 for reducing to quadratic form \(x^2 - 3x - 10 = 0\). A1 for both correct answers: \(x = 5\) and \(x = -2\).
Question 18 · short_answer
3 marks
Find the coordinates of the point on the curve \(y = x^2 - 4x + 7\) where the gradient of the curve is 2.
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Worked solution
First, find the derivative of the curve equation to get the gradient function: \(\frac{dy}{dx} = 2x - 4\). Set the gradient equal to 2: \(2x - 4 = 2\). Solve for \(x\): \(2x = 6 \implies x = 3\). Substitute \(x = 3\) back into the original curve equation to find the corresponding y-coordinate: \(y = 3^2 - 4(3) + 7 = 9 - 12 + 7 = 4\). Thus, the coordinates of the point are \((3, 4)\).
Marking scheme
M1 for differentiating to obtain \(2x - 4\). M1 for setting their derivative equal to 2 and solving to find \(x = 3\). A1 for correct coordinates \((3, 4)\).
Question 19 · short_answer
3 marks
In a triangle \(ABC\), \(AB = 7\text{ cm}\), \(BC = 9\text{ cm}\), and angle \(ABC = 120^\circ\). Calculate the length of \(AC\).
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Worked solution
Using the Cosine Rule to find the side \(AC\): \(AC^2 = AB^2 + BC^2 - 2 \cdot AB \cdot BC \cdot \cos(ABC)\). Substitute the given values into the formula: \(AC^2 = 7^2 + 9^2 - 2(7)(9)\cos(120^\circ)\). Since \(\cos(120^\circ) = -0.5\), this simplifies to: \(AC^2 = 49 + 81 - 126(-0.5) = 130 + 63 = 193\). Calculate \(AC\): \(AC = \sqrt{193} \approx 13.892\text{ cm}\). Rounding to 3 significant figures gives \(13.9\text{ cm}\).
Marking scheme
M1 for correct substitution into the Cosine Rule: \(7^2 + 9^2 - 2(7)(9)\cos(120^\circ)\). M1 for \(AC^2 = 193\) or \(AC = \sqrt{193}\). A1 for \(13.9\) or \(13.89\dots\) (accept 13.9).
Question 20 · short_answer
3 marks
A solid cone has a base radius of \(4\text{ cm}\) and a slant height of \(9\text{ cm}\). Calculate the total surface area of the cone, leaving your answer in terms of \(\pi\).
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Worked solution
The total surface area of a cone is the sum of the base area and the curved surface area: \(A = \pi r^2 + \pi r l\), where \(r\) is the radius and \(l\) is the slant height. Substitute \(r = 4\) and \(l = 9\): \(A = \pi(4)^2 + \pi(4)(9) = 16\pi + 36\pi = 52\pi\text{ cm}^2\).
Marking scheme
M1 for calculating base area as \(16\pi\) or curved surface area as \(36\pi\). M1 for adding the two areas together, i.e., \(\pi(4)^2 + \pi(4)(9)\). A1 for \(52\pi\).
Question 21 · short_answer
3 marks
In a sale, the price of a laptop is first reduced by 20%. A week later, this reduced price is reduced by a further 10%. The final sale price is $576. Calculate the original price of the laptop.
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Worked solution
Let the original price of the laptop be \(P\). After the first reduction of 20%, the price is \(0.80P\). After the second reduction of 10%, the price becomes \(0.90 \times 0.80P = 0.72P\). We are given that \(0.72P = 576\). Solving for \(P\): \(P = \frac{576}{0.72} = 800\). Thus, the original price of the laptop was $800.
Marking scheme
M1 for identifying multipliers \(0.80\) and \(0.90\) (or equivalent). M1 for setting up the equation \(0.72P = 576\) or performing the calculation \(576 \div 0.9 \div 0.8\). A1 for 800.
Question 22 · short_answer
3 marks
A regular polygon has an interior angle that is \(140^\circ\) larger than its exterior angle. Find the number of sides of this polygon.
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Worked solution
Let the exterior angle of the polygon be \(x^\circ\). The interior angle is therefore \((x + 140)^\circ\). Since the interior angle and exterior angle at any vertex of a polygon sum to \(180^\circ\), we have: \(x + (x + 140) = 180 \implies 2x + 140 = 180 \implies 2x = 40 \implies x = 20\). The exterior angle is \(20^\circ\). The number of sides \(n\) is given by: \(n = \frac{360^\circ}{\text{exterior angle}} = \frac{360}{20} = 18\).
Marking scheme
M1 for setting up an equation for the angles, e.g. \(x + (x+140) = 180\). M1 for finding the exterior angle is \(20^\circ\) or interior angle is \(160^\circ\). A1 for 18.
Question 23 · short_answer
3 marks
Solve the equation \(27^{x-1} = 9^{2x-5}\).
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Worked solution
Express both bases as powers of 3: \(27 = 3^3\) and \(9 = 3^2\). Substitute these back into the equation: \((3^3)^{x-1} = (3^2)^{2x-5}\). Apply the index law \((a^m)^n = a^{mn}\): \(3^{3(x-1)} = 3^{2(2x-5)}\). Since the bases are now identical, equate the exponents: \(3(x-1) = 2(2x-5)\). Expand and solve: \(3x - 3 = 4x - 10 \implies 10 - 3 = 4x - 3x \implies x = 7\).
Marking scheme
M1 for writing 27 as \(3^3\) and 9 as \(3^2\) (or alternative common base). M1 for equating the exponents: \(3(x-1) = 2(2x-5)\) or better. A1 for 7.
Paper 32 (Core)
Answer all questions. Use of a calculator is permitted where appropriate. Show all necessary working clearly.
(b) Solve the simultaneous equations: $$3x + 2y = 12$$ $$4x - y = 5$$
(c) A rectangle has length $(2x + 3)\text{ cm}$ and width $x\text{ cm}$. Its perimeter is $30\text{ cm}$. Form an equation in $x$ and solve it to find the value of $x$.
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(b) Multiply the second equation by 2: $$8x - 2y = 10$$ Add this to the first equation: $$(3x + 2y) + (8x - 2y) = 12 + 10$$ $$11x = 22$$ $$x = 2$$ Substitute $x = 2$ into the second equation: $$4(2) - y = 5$$ $$8 - y = 5 \Rightarrow y = 3$$ So, $x = 2$ and $y = 3$.
(a) M1 for expanding: $5x - 15 - 2x - 2 = 7$ M1 for simplifying to: $3x - 17 = 7$ M1 for rearranging: $3x = 24$ A1 for final answer $x = 8$
(b) M1 for multiplying second equation to get $8x - 2y = 10$ (or equivalent) M1 for adding equations to eliminate $y$ A1 for $x = 2$ M1 for substituting their $x$ to find $y$ A0.5 for $y = 3$
(c) M1 for setting up the equation $2(2x + 3 + x) = 30$ (or equivalent) M1 for simplifying to $6x + 6 = 30$ A1 for final answer $x = 4$
Question 2 · structured
11.5 marks
Consider the quadratic function $y = x^2 - 2x - 3$.
(a) Complete the table of values for this function: $$ \begin{array}{|c|c|c|c|c|c|c|c|} \hline x & -2 & -1 & 0 & 1 & 2 & 3 & 4 \\ \hline y & P & 0 & -3 & Q & -3 & 0 & R \\ \hline \end{array} $$ Find the values of $P$, $Q$, and $R$.
(b) Use the values to identify the solutions to the equation: $$x^2 - 2x - 3 = 0$$
(c) Write down the coordinates of the turning point (minimum point) of the curve.
(d) Write down the equation of the line of symmetry of this curve.
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(b) The solutions to $x^2 - 2x - 3 = 0$ are the values of $x$ where $y = 0$. From the table, these are $x = -1$ and $x = 3$.
(c) The minimum point occurs at the vertex. By symmetry, the $x$-coordinate is halfway between the roots: $x = 1$. The corresponding $y$-value is $-4$. So the turning point is $(1, -4)$.
(d) The line of symmetry is the vertical line passing through the turning point, which has the equation $x = 1$.
Marking scheme
(a) B1 for $P = 5$, B1 for $Q = -4$, B1.5 for $R = 5$
(b) B1 for $x = -1$, B1 for $x = 3$ (or M1 for identifying where $y = 0$)
(c) B1 for $x$-coordinate of 1, B1 for $y$-coordinate of -4 (Accept $(1, -4)$)
(d) B2 for $x = 1$ (B1 for just '1' or 'x = ...' with wrong value, or drawing the correct vertical line on a sketch)
Question 3 · structured
11.5 marks
In triangle $ABC$, the length of side $AB = 8.5\text{ cm}$, the length of side $BC = 6.2\text{ cm}$, and angle $ABC = 75^\circ$.
(a) Calculate the area of triangle $ABC$.
(b) Use the cosine rule to calculate the length of side $AC$. Give your answer correct to 3 significant figures.
(c) Use the sine rule to find the angle $ACB$. Give your answer correct to 1 decimal place.
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Worked solution
(a) The area of a triangle is given by: $$\text{Area} = \frac{1}{2} a c \sin B$$ $$\text{Area} = \frac{1}{2} \times 6.2 \times 8.5 \times \sin(75^\circ)$$ $$\text{Area} = 26.35 \times 0.9659258... \approx 25.45\text{ cm}^2$$ To 3 significant figures, this is $25.5\text{ cm}^2$.
(c) Using the Sine Rule: $$\frac{\sin(ACB)}{AB} = \frac{\sin(ABC)}{AC}$$ $$\frac{\sin(ACB)}{8.5} = \frac{\sin(75^\circ)}{9.1329}$$ $$\sin(ACB) = \frac{8.5 \times \sin(75^\circ)}{9.1329} \approx \frac{8.21037}{9.1329} \approx 0.8990$$ $$\text{Angle } ACB = \sin^{-1}(0.8990) \approx 64.03^\circ$$ To 1 decimal place, angle $ACB = 64.0^\circ$.
Marking scheme
(a) M1 for $\frac{1}{2} \times 6.2 \times 8.5 \times \sin(75^\circ)$ M1 for $26.35 \times \sin(75^\circ)$ A1.5 for $25.5$ (or $25.45$)
(b) M1 for correct substitution into Cosine Rule: $6.2^2 + 8.5^2 - 2(6.2)(8.5)\cos(75^\circ)$ M1 for correct evaluation of terms: $110.69 - 27.28$ A1 for $AC^2 = 83.4$ A1 for $AC = 9.13$
(c) M1 for correct Sine Rule setup: $\frac{\sin(ACB)}{8.5} = \frac{\sin(75^\circ)}{9.13}$ M1 for rearrangement: $\sin(ACB) = \frac{8.5 \sin(75^\circ)}{9.13}$ A1 for $\sin(ACB) \approx 0.899$ A1 for angle $ACB = 64.0^\circ$ (accept $64.0$ to $64.1$ depending on rounding of AC)
Question 4 · structured
11.5 marks
A solid closed cylinder has a radius of $4.5\text{ cm}$ and a height of $12\text{ cm}$.
(a) Calculate the volume of the cylinder. Give your answer correct to 3 significant figures.
(b) Calculate the total surface area of the cylinder. Give your answer correct to 3 significant figures.
(c) The cylinder is melted down and recast into a solid sphere. The volume of a sphere is given by $V = \frac{4}{3}\pi r^3$. Calculate the radius of this sphere. Give your answer correct to 3 significant figures.
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Worked solution
(a) The volume of a cylinder is: $$V = \pi r^2 h = \pi \times 4.5^2 \times 12 = 243\pi \approx 763.407...\text{ cm}^3$$ To 3 significant figures, $V = 763\text{ cm}^3$.
(b) The total surface area of a closed cylinder is: $$A = 2\pi r^2 + 2\pi r h = 2\pi(4.5^2) + 2\pi(4.5)(12) = 40.5\pi + 108\pi = 148.5\pi \approx 466.526...\text{ cm}^2$$ To 3 significant figures, $A = 467\text{ cm}^2$.
(c) The volume of the sphere is equal to the volume of the cylinder: $$\frac{4}{3}\pi R^3 = 243\pi$$ Divide both sides by $\pi$: $$\frac{4}{3} R^3 = 243$$ Multiply by $\frac{3}{4}$: $$R^3 = 243 \times \frac{3}{4} = 182.25$$ $$R = \sqrt[3]{182.25} \approx 5.6696...\text{ cm}$$ To 3 significant figures, the radius is $5.67\text{ cm}$.
Marking scheme
(a) M1 for formula $\pi r^2 h$ M1 for substituting: $\pi \times 4.5^2 \times 12$ A1.5 for $763$ (or $763.4$)
(b) M1 for area of circular ends: $2 \times \pi \times 4.5^2 = 40.5\pi$ M1 for curved surface area: $2 \times \pi \times 4.5 \times 12 = 108\pi$ A2 for $467$ (or $466.5$)
(c) M1 for equating volumes: $\frac{4}{3}\pi R^3 = 243\pi$ (or $763$) M1 for isolating $R^3$: $R^3 = 182.25$ M1 for finding cube root: $R = \sqrt[3]{182.25}$ A1 for $5.67$ (accept $5.66$ to $5.68$)
Question 5 · structured
11.5 marks
Work out the following:
(a) Find $\frac{3}{8}$ of $1440$.
(b) In a holiday season sale, the price of a bicycle is reduced by $15\%$. The sale price is $306$. Calculate the original price of the bicycle before the discount.
(c) The price of a laptop increases from $450$ to $513$. Calculate the percentage increase.
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Worked solution
(a) Calculation: $$\frac{3}{8} \times 1440 = 3 \times 180 = 540$$ So, $\frac{3}{8}$ of $1440$ is $540$.
(b) Let the original price be $P$. A $15\%$ reduction means the sale price is $85\%$ of the original price: $$0.85 \times P = 306$$ $$P = \frac{306}{0.85} = 360$$ So, the original price was $360$.
(c) First find the increase in price: $$\text{Increase} = 513 - 450 = 63$$ Now, calculate the percentage increase relative to the original price: $$\text{Percentage Increase} = \frac{63}{450} \times 100\%$$ $$\text{Percentage Increase} = 0.14 \times 100\% = 14\%$$ So, the price increased by $14\%$.
Marking scheme
(a) M1.5 for $\frac{3}{8} \times 1440$ A1 for $540$
(b) M1 for setting up relation: $0.85 \times P = 306$ (or $85\% = 306$) M2 for $\frac{306}{0.85}$ (or $\frac{306}{85} \times 100$) A1 for $360$
(c) M1.5 for finding the difference: $513 - 450 = 63$ M2.5 for dividing by original: $\frac{63}{450} \times 100$ A1 for $14$ or $14\%$
Question 6 · structured
11.5 marks
(a) A regular polygon has an exterior angle of $24^\circ$.
(i) Find the number of sides of this polygon.
(ii) Find the sum of the interior angles of this polygon.
(b) In a diagram, two parallel lines are crossed by a straight line. Two co-interior angles are represented by $(3x + 15)^\circ$ and $(2x + 10)^\circ$.
(i) Set up an equation and solve it to find the value of $x$.
(ii) Hence, find the size of the larger of these two angles.
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Worked solution
(a)(i) The sum of exterior angles of any polygon is $360^\circ$. $$\text{Number of sides} = \frac{360^\circ}{24^\circ} = 15$$ There are 15 sides.
(a)(ii) The sum of interior angles of an $n$-sided polygon is given by $(n - 2) \times 180^\circ$: $$\text{Sum} = (15 - 2) \times 180^\circ = 13 \times 180^\circ = 2340^\circ$$
(b)(i) Co-interior angles between parallel lines add up to $180^\circ$: $$(3x + 15) + (2x + 10) = 180$$ $$5x + 25 = 180$$ $$5x = 155$$ $$x = 31$$
(b)(ii) Find the size of both angles by substituting $x = 31$: - Angle 1: $3(31) + 15 = 93 + 15 = 108^\circ$ - Angle 2: $2(31) + 10 = 62 + 10 = 72^\circ$ The larger angle is $108^\circ$.
Marking scheme
(a)(i) M1 for $\frac{360}{24}$ A1.5 for $15$
(a)(ii) M1.5 for $(15-2) \times 180$ (allow follow through on their sides) A1.5 for $2340$
(b)(i) M1 for setting up the equation: $(3x+15) + (2x+10) = 180$ M1.5 for simplifying to: $5x + 25 = 180$ or $5x = 155$ A1.5 for $x = 31$
(b)(ii) M1 for substituting $x = 31$ into $3x + 15$ or $2x + 10$ A1 for $108$
Question 7 · structured
11.5 marks
(a) Share $450$ in the ratio $2 : 3 : 4$. Find the value of each share.
(b) The mass of a metal bar is directly proportional to its length. A bar of length $1.2\text{ m}$ has a mass of $4.8\text{ kg}$.
(i) Find the constant of proportionality $k$ such that $\text{mass} = k \times \text{length}$.
(ii) Find the mass of a bar made of the same metal that has a length of $3.5\text{ m}$.
(c) A recipe for 8 people requires $600\text{ g}$ of flour. Calculate the amount of flour needed for 14 people.
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Worked solution
(a) Sum of parts of the ratio: $$2 + 3 + 4 = 9$$ Value of one part: $$\frac{450}{9} = 50$$ Multiply each part by 50: - First share: $2 \times 50 = 100$ - Second share: $3 \times 50 = 150$ - Third share: $4 \times 50 = 200$ So the shares are $100, $150, and $200.
(b)(i) Given relation: $$\text{mass} = k \times \text{length}$$ $$4.8 = k \times 1.2$$ $$k = \frac{4.8}{1.2} = 4$$
(b)(ii) Use the equation $\text{mass} = 4 \times \text{length}$: $$\text{mass} = 4 \times 3.5 = 14\text{ kg}$$
(c) Use unit proportion: $$\text{Flour per person} = \frac{600\text{ g}}{8} = 75\text{ g}$$ For 14 people: $$\text{Flour needed} = 14 \times 75\text{ g} = 1050\text{ g}$$
Marking scheme
(a) M1 for finding sum of ratio parts: $2+3+4 = 9$ M1.5 for dividing $450$ by $9$ A1 for final shares: $100, $150, $200 (must have all three correct for full marks)
(b)(i) M1.5 for substituting values into formula: $4.8 = k \times 1.2$ A1 for $k = 4$
(b)(ii) M1 for substituting $3.5$ into formula: $\text{mass} = 4 \times 3.5$ A1 for $14\text{ kg}$
(c) M1.5 for finding flour per person: $\frac{600}{8} = 75$ M1 for multiplying by 14: $14 \times 75$ A1 for $1050\text{ g}$
Question 8 · structured
11.5 marks
A box contains 8 red pens, 5 blue pens, and some green pens. A pen is chosen at random from the box.
(a) The probability of choosing a blue pen is $\frac{1}{4}$.
(i) Show that the total number of pens in the box is 20.
(ii) Find the number of green pens in the box.
(b) A pen is chosen at random from the 20 pens in the box. Find the probability that the pen is:
(i) Red
(ii) Not blue
(iii) Yellow
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Worked solution
(a)(i) Let $N$ be the total number of pens. The probability of choosing a blue pen is given by: $$\frac{\text{Number of blue pens}}{N} = \frac{1}{4}$$ $$\frac{5}{N} = \frac{1}{4}$$ Multiply both sides by $4N$: $$20 = N$$ Thus, the total number of pens in the box is 20.
(a)(ii) The number of green pens is the total number minus the other colors: $$\text{Green pens} = 20 - 8\text{ (red)} - 5\text{ (blue)} = 7\text{ green pens}$$
(b)(i) Probability of choosing a red pen: $$P(\text{Red}) = \frac{\text{Number of red pens}}{\text{Total pens}} = \frac{8}{20} = \frac{2}{5} = 0.4$$
(b)(ii) Probability of choosing a pen that is not blue: $$P(\text{Not Blue}) = 1 - P(\text{Blue}) = 1 - \frac{1}{4} = \frac{3}{4} = 0.75$$ Alternatively, count other colors: $8\text{ (red)} + 7\text{ (green)} = 15$ pens. So $P(\text{Not Blue}) = \frac{15}{20} = \frac{3}{4}$.
(b)(iii) Since there are no yellow pens in the box, the probability is $0$.
Marking scheme
(a)(i) M2 for setting up equation: $\frac{5}{N} = \frac{1}{4}$ or stating $5 \times 4 = 20$ A1.5 for showing clearly $N = 20$
(a)(ii) M1 for subtraction: $20 - 8 - 5$ A1 for $7$
(b)(i) M1 for $\frac{8}{20}$ (or equivalent) A1 for $\frac{2}{5}$ (or $0.4$)
(b)(ii) M1 for $1 - \frac{1}{4}$ or $\frac{15}{20}$ A1 for $\frac{3}{4}$ (or $0.75$)
(b)(iii) B2 for $0$ (or 'impossible')
Question 9 · structured
11.5 marks
A wooden block is in the shape of a triangular prism. The cross-section of the prism is a right-angled triangle with a base of 6 cm and a height of 8 cm. The length of the prism is 15 cm. (a) Calculate the volume of the wooden block. (b) Show that the hypotenuse of the triangular cross-section is 10 cm. (c) Calculate the total surface area of the wooden block. (d) The wood has a density of 0.65 g/cm^3. Calculate the mass of the wooden block. (e) A tin of paint can cover 2.5 m^2. Calculate the maximum number of complete wooden blocks that can be painted with one tin of paint.
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Worked solution
(a) Area of the triangular cross-section = 0.5 * base * height = 0.5 * 6 * 8 = 24 cm^2. Volume = Area of cross-section * length = 24 * 15 = 360 cm^3. (b) Using Pythagoras' theorem: hypotenuse^2 = 6^2 + 8^2 = 36 + 64 = 100. Taking the square root gives hypotenuse = sqrt(100) = 10 cm. (c) Total surface area is the sum of the areas of the 2 triangular faces and 3 rectangular faces. Area of 2 triangular faces = 2 * 24 = 48 cm^2. Area of rectangular faces = (6 * 15) + (8 * 15) + (10 * 15) = 90 + 120 + 150 = 360 cm^2. Total surface area = 48 + 360 = 408 cm^2. (d) Mass = Density * Volume = 0.65 * 360 = 234 g. (e) First, convert the coverage area of the paint from square meters to square centimeters: 2.5 m^2 = 2.5 * 10000 = 25000 cm^2. Number of blocks that can be painted = 25000 / 408 = 61.27... Since only complete blocks can be painted, the maximum number of complete wooden blocks is 61.
Marking scheme
(a) M1 for 0.5 * 6 * 8, M1 for multiplying their cross-section area by 15, A1 for 360. (b) M1 for 6^2 + 8^2 or sqrt(6^2 + 8^2), A1 for showing it equals 10. (c) M1 for calculating the sum of the rectangular areas (e.g., (6+8+10)*15), M1 for adding the area of the two triangular faces (e.g., 2 * 24), A1 for 408. (d) M1 for 360 * 0.65, A1 for 234. (e) M1 for converting 2.5 m^2 to 25000 cm^2 (or converting 408 cm^2 to 0.0408 m^2), A0.5 for 61 (rounded down to the nearest integer).
Paper 42 (Extended)
Answer all questions. Use of a calculator is permitted where appropriate. Show all necessary working clearly.
10 Question · 130 marks
Question 1 · structured
13 marks
Liam invests $8000 in a savings account paying compound interest of \(r\%\) per year. At the end of 3 years, the value of his investment is $8741.81. (a) Find the value of \(r\). [4] (b) Liam also buys a car. The value of the car depreciates exponentially at a rate of 12% per year. After 2 years, its value is $13552. Calculate the original price of the car. [3] (c) Liam sells his laptop to a friend for $468. This is a loss of 28% on the price he originally paid. Calculate the price Liam originally paid for the laptop. [3] (d) In a sale, the price of a bicycle is reduced by 15%. The sale price is then reduced by a further 10%. Work out the single percentage reduction that is equivalent to these two reductions. [3]
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Worked solution
(a) Using the compound interest formula: \(8000(1 + r/100)^3 = 8741.81\). Dividing by 8000: \((1 + r/100)^3 = 1.092726\). Taking the cube root: \(1 + r/100 = 1.03\), which gives \(r = 3\). (b) Using the depreciation formula: \(P(1 - 0.12)^2 = 13552 \implies P(0.88)^2 = 13552 \implies 0.7744P = 13552 \implies P = 17500\). (c) Let the original price be \(L\). A 28% loss means he sold it for 72% of the original price: \(0.72L = 468 \implies L = 650\). (d) Let the original price be 100%. After a 15% reduction, the price is 85%. After a further 10% reduction, the price becomes \(85\% \times 0.9 = 76.5\%\). The equivalent single reduction is \(100\% - 76.5\% = 23.5\%\).
Marking scheme
(a) M1 for \(8000(1 + r/100)^3 = 8741.81\), M1 for \((1 + r/100)^3 = 1.092726\), M1 for \(1 + r/100 = 1.03\), A1 for \(r = 3\). (b) M1 for \(P(0.88)^2 = 13552\), M1 for \(13552 / 0.7744\), A1 for 17500. (c) M1 for \(0.72L = 468\), M1 for \(468 / 0.72\), A1 for 650. (d) M1 for \(0.85 \times 0.90\), M1 for \(1 - 0.765\), A1 for 23.5%.
Question 2 · structured
13 marks
A cyclist travels 36 km at an average speed of \(x\) km/h. (a) Write down an expression, in terms of \(x\), for the time taken in hours. [1] (b) The cyclist travels another 45 km at an average speed of \((x - 3)\) km/h. Write down an expression, in terms of \(x\), for the time taken in hours. [1] (c) The total time for the two journeys is 4.5 hours. Show that \(x^2 - 21x + 24 = 0\). [5] (d) Solve the equation \(x^2 - 21x + 24 = 0\), showing all your working. Give your answers correct to 2 decimal places. [4] (e) Find the time taken to travel the first 36 km, giving your answer in hours and minutes, to the nearest minute. [2]
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Worked solution
(a) Time = Distance / Speed = \(\frac{36}{x}\). (b) Time = \(\frac{45}{x-3}\). (c) Total time is given by \(\frac{36}{x} + \frac{45}{x-3} = 4.5\). Divide by 4.5 to simplify: \(\frac{8}{x} + \frac{10}{x-3} = 1\). Multiply both sides by \(x(x-3)\): \(8(x-3) + 10x = x(x-3) \implies 8x - 24 + 10x = x^2 - 3x \implies 18x - 24 = x^2 - 3x \implies x^2 - 21x + 24 = 0\). (d) Using the quadratic formula: \(x = \frac{21 \pm \sqrt{(-21)^2 - 4(1)(24)}}{2} = \frac{21 \pm \sqrt{345}}{2}\). This gives \(x = \frac{21 \pm 18.574}{2}\), so \(x \approx 19.79\) or \(x \approx 1.21\). (e) Since the speed in the second part is \(x-3\), we must have \(x > 3\). Thus, \(x = 19.79\). Time for the first 36 km is \(\frac{36}{19.79} \approx 1.819\) hours. Multiplying the fractional part by 60: \(0.819 \times 60 = 49.1\) minutes. This gives 1 hour and 49 minutes to the nearest minute.
Marking scheme
(a) B1 for \(\frac{36}{x}\). (b) B1 for \(\frac{45}{x-3}\). (c) M1 for \(\frac{36}{x} + \frac{45}{x-3} = 4.5\), M1 for algebraic step to remove denominators: \(36(x-3) + 45x = 4.5x(x-3)\), M1 for expanding: \(36x - 108 + 45x = 4.5x^2 - 13.5x\), M1 for rearranging to quadratic form: \(4.5x^2 - 94.5x + 108 = 0\), A1 for dividing by 4.5 to reach \(x^2 - 21x + 24 = 0\). (d) M1 for correct substitution into quadratic formula, M1 for evaluation of discriminant as 345, A1 for \(x = 19.79\), A1 for \(x = 1.21\). (e) M1 for substituting \(x = 19.79\) into \(\frac{36}{x}\), A1 for 1 hour 49 minutes.
Question 3 · structured
13 marks
Consider the curve with equation \(y = x^3 - 3x^2 - 9x + 5\). (a) Find the coordinates of the two turning points of the curve. [5] (b) The equation \(x^3 - 3x^2 - 9x + 5 = k\) has exactly two distinct real solutions. Find the two possible values of the constant \(k\). [3] (c) Find the equation of the tangent to the curve at the point where \(x = 1\). Give your answer in the form \(y = mx + c\). [5]
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Worked solution
(a) Differentiate the function to find the gradient: \(\frac{dy}{dx} = 3x^2 - 6x - 9\). Set \(\frac{dy}{dx} = 0\) for turning points: \(3x^2 - 6x - 9 = 0 \implies x^2 - 2x - 3 = 0 \implies (x-3)(x+1) = 0\). This gives \(x = 3\) or \(x = -1\). When \(x = 3\), \(y = 3^3 - 3(3)^2 - 9(3) + 5 = -22\). When \(x = -1\), \(y = (-1)^3 - 3(-1)^2 - 9(-1) + 5 = 10\). The turning points are \((3, -22)\) and \((-1, 10)\). (b) A horizontal line \(y = k\) intersects a cubic curve exactly twice only when it passes through one of its local extrema (the turning points). Hence, \(k = 10\) or \(k = -22\). (c) When \(x = 1\), the y-coordinate is \(y = 1^3 - 3(1)^2 - 9(1) + 5 = -6\). The gradient of the tangent at \(x = 1\) is \(\frac{dy}{dx}\big|_{x=1} = 3(1)^2 - 6(1) - 9 = -12\). Using the point-slope form of a straight line: \(y - (-6) = -12(x - 1) \implies y + 6 = -12x + 12 \implies y = -12x + 6\).
Marking scheme
(a) M1 for \(\frac{dy}{dx} = 3x^2 - 6x - 9\), M1 for setting their derivative to 0, A1 for \(x = 3\) and \(x = -1\), A1 for \(y = -22\), A1 for \(y = 10\). (b) M2 for recognizing that \(k\) must equal the y-coordinates of the turning points (M1 for identifying one correct y-value), A1 for \(k = 10\) and \(k = -22\). (c) M1 for finding \(y = -6\) when \(x = 1\), M1 for substituting \(x = 1\) into their \(\frac{dy}{dx}\), A1 for gradient \(m = -12\), M1 for substituting their point and gradient into a straight line equation, A1 for \(y = -12x + 6\).
Question 4 · structured
13 marks
A surveyor measures three points \(A\), \(B\), and \(C\) on a flat field. \(B\) is on a bearing of \(065^\circ\) from \(A\) and \(AB = 120\) m. \(C\) is on a bearing of \(135^\circ\) from \(A\), and \(AC = 180\) m. (a)(i) Show that angle \(BAC = 70^\circ\). [1] (a)(ii) Calculate the distance \(BC\). [3] (a)(iii) Calculate the bearing of \(C\) from \(B\). [4] (b) Calculate the area of triangle \(ABC\). [2] (c) A straight path runs from \(A\) to \(BC\). Find the shortest distance from \(A\) to the path \(BC\). [3]
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Worked solution
(a)(i) Angle \(BAC = 135^\circ - 65^\circ = 70^\circ\). (a)(ii) Using the Cosine rule on triangle \(ABC\): \(BC^2 = AB^2 + AC^2 - 2(AB)(AC)\cos(BAC) = 120^2 + 180^2 - 2(120)(180)\cos(70^\circ) = 14400 + 32400 - 43200(0.34202) = 46800 - 14775.3 = 32024.7\). Hence, \(BC = \sqrt{32024.7} \approx 178.95\) m, which rounds to 179 m to 3 s.f. (a)(iii) First, find angle \(ABC\) using the Cosine rule: \(\cos(ABC) = \frac{120^2 + 178.95^2 - 180^2}{2(120)(178.95)} = \frac{14024.7}{42948} = 0.32655 \implies \text{Angle } ABC \approx 70.94^\circ\). The bearing of \(A\) from \(B\) is \(65^\circ + 180^\circ = 245^\circ\). Since \(C\) lies clockwise to the line \(BA\) looking from \(B\), the bearing of \(C\) from \(B\) is \(245^\circ - 70.94^\circ = 174.06^\circ\), which is \(174.1^\circ\) to 1 d.p. (b) Area of triangle \(ABC = \frac{1}{2} \times AB \times AC \times \sin(BAC) = \frac{1}{2} \times 120 \times 180 \times \sin(70^\circ) = 10800 \times 0.93969 = 10148.6\text{ m}^2\), or 10100 \(\text{m}^2\) to 3 s.f. (c) The shortest distance \(d\) from \(A\) to \(BC\) is the perpendicular height. Area = \(\frac{1}{2} \times BC \times d \implies 10148.6 = \frac{1}{2} \times 178.95 \times d \implies d \approx 113.4\) m, or 113 m to 3 s.f.
Marking scheme
(a)(i) B1 for \(135 - 65 = 70\). (a)(ii) M1 for correct substitution into Cosine rule: \(120^2 + 180^2 - 2(120)(180)\cos(70)\), M1 for evaluation to \(32025\), A1 for \(179\) or \(178.95\). (a)(iii) M1 for Cosine rule or Sine rule to find angle \(ABC\), A1 for angle \(ABC = 70.9^\circ\) (or \(71^\circ\)), M1 for establishing bearing relation (e.g. \(245^\circ - 70.9^\circ\)), A1 for \(174.1^\circ\) (or \(174^\circ\)). (b) M1 for \(\frac{1}{2} \times 120 \times 180 \times \sin(70)\), A1 for 10100 or 10150. (c) M1 for equating area to \(\frac{1}{2} \times \text{their } BC \times d\), M1 for rearranging to make \(d\) the subject, A1 for 113 or 113.4.
Question 5 · structured
13 marks
A solid metal toy is made of a hemisphere of radius \(r\) surmounted by a cone of radius \(r\) and height \(h\). (a) Write down an expression for the total volume of the toy in terms of \(\pi\), \(r\), and \(h\). [2] (b) The total volume of the toy is \(360\pi\text{ cm}^3\). (i) Given that the height of the cone \(h\) is equal to \(3r\), show that \(r = 6\) cm. [3] (ii) Find the height of the cone. [1] (c) Calculate the total surface area of the toy. [5] (d) The toy is made of metal with a density of \(7.8\text{ g/cm}^3\). Calculate the mass of the toy in kilograms. [2]
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Worked solution
(a) Volume of hemisphere = \(\frac{2}{3}\pi r^3\). Volume of cone = \(\frac{1}{3}\pi r^2 h\). Total volume = \(\frac{2}{3}\pi r^3 + \frac{1}{3}\pi r^2 h\). (b)(i) Since \(h = 3r\), Total Volume = \(\frac{2}{3}\pi r^3 + \frac{1}{3}\pi r^2(3r) = \frac{2}{3}\pi r^3 + \pi r^3 = \frac{5}{3}\pi r^3\). Set this equal to \(360\pi\): \(\frac{5}{3}\pi r^3 = 360\pi \implies \frac{5}{3}r^3 = 360 \implies r^3 = 216 \implies r = 6\) cm. (b)(ii) \(h = 3r = 3(6) = 18\) cm. (c) Total surface area = Curved surface area of hemisphere + Curved surface area of cone. CSA of hemisphere = \(2\pi r^2 = 2\pi (6^2) = 72\pi \approx 226.19\text{ cm}^2\). Slant height of cone \(l = \sqrt{r^2 + h^2} = \sqrt{6^2 + 18^2} = \sqrt{360} \approx 18.974\) cm. CSA of cone = \(\pi r l = \pi (6)(18.974) \approx 357.64\text{ cm}^2\). Total Surface Area = \(226.19 + 357.64 \approx 583.83\text{ cm}^2\), or 584 \(\text{cm}^2\) to 3 s.f. (d) Mass = Volume \(\times\) Density. Volume = \(360\pi \approx 1130.97\text{ cm}^3\). Mass = \(1130.97 \times 7.8 = 8821.59\) g. In kg, Mass = \(8821.59 / 1000 \approx 8.82\) kg.
Marking scheme
(a) B1 for hemisphere volume formula, B1 for cone volume formula. (b)(i) M1 for substituting \(h = 3r\) into their volume expression, M1 for setting \(\frac{5}{3}\pi r^3 = 360\pi\), A1 for \(r^3 = 216\) leading to \(r = 6\). (b)(ii) B1 for 18. (c) M1 for CSA of hemisphere = \(2\pi(6)^2\), M1 for finding slant height \(l = \sqrt{6^2 + 18^2}\) (or \(\sqrt{360}\)), M1 for CSA of cone = \(\pi(6)(\sqrt{360})\), M1 for adding the two curved surface areas, A1 for 584 or 583.8. (d) M1 for finding actual volume in \(\text{cm}^3\) (approx 1131), M1 for \(1130.97 \times 7.8 / 1000\), A1 for 8.82.
Question 6 · structured
13 marks
In a circle with centre \(O\), \(A\), \(B\), and \(C\) are points on the circumference. Tangents to the circle at \(A\) and \(B\) meet at the point \(T\). The angle \(ATB = 48^\circ\). (a)(i) Calculate angle \(AOB\). Give reasons for your answer. [3] (a)(ii) Calculate angle \(ACB\), where \(C\) is a point on the major arc \(AB\). [2] (a)(iii) Find angle \(OAB\). [2] (b) An interior angle of a regular polygon is \(168^\circ\). (i) Calculate the number of sides of this polygon. [3] (ii) Calculate the sum of the interior angles of this polygon. [3]
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Worked solution
(a)(i) Tangents \(TA\) and \(TB\) are perpendicular to the radii \(OA\) and \(OB\) respectively, so angle \(OAT = OBT = 90^\circ\). Since the sum of angles in a quadrilateral is \(360^\circ\), angle \(AOB = 360^\circ - 90^\circ - 90^\circ - 48^\circ = 132^\circ\). (a)(ii) The angle subtended by an arc at the centre is twice the angle subtended at the circumference. Thus, angle \(ACB = 132^\circ / 2 = 66^\circ\). (a)(iii) In triangle \(OAB\), \(OA = OB\) (both are radii), so triangle \(OAB\) is isosceles. Therefore, angle \(OAB = (180^\circ - 132^\circ) / 2 = 24^\circ\). (b)(i) Each exterior angle of a regular polygon is \(180^\circ - \text{interior angle} = 180^\circ - 168^\circ = 12^\circ\). The sum of exterior angles of any polygon is \(360^\circ\). Thus, number of sides \(n = 360 / 12 = 30\). (b)(ii) Sum of interior angles = \((n - 2) \times 180^\circ = (30 - 2) \times 180^\circ = 28 \times 180^\circ = 5040^\circ\).
Marking scheme
(a)(i) B1 for identifying tangent-radius angle is \(90^\circ\), M1 for \(360 - 90 - 90 - 48\), A1 for 132. (a)(ii) M1 for \(132 / 2\), A1 for 66. (a)(iii) M1 for realizing \(OA=OB\) and setting up equation, A1 for 24. (b)(i) M1 for exterior angle = \(180 - 168\), M1 for \(360 / 12\), A1 for 30. (b)(ii) M1 for \((n-2) \times 180\) or \(30 \times 168\), M1 for substituting \(n = 30\), A1 for 5040.
Question 7 · structured
13 marks
(a) Write as a single fraction in its simplest form: \(\frac{4}{2x - 3} - \frac{3}{x + 5}\). [4] (b) Simplify fully: \(\frac{2x^2 - 5x - 3}{4x^2 - 1}\). [4] (c) Solve the equation: \(\frac{5}{x - 2} + \frac{2}{x + 1} = 3\). [5]
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Worked solution
(a) Placing over a common denominator: \(\frac{4(x + 5) - 3(2x - 3)}{(2x - 3)(x + 5)} = \frac{4x + 20 - 6x + 9}{(2x - 3)(x + 5)} = \frac{29 - 2x}{(2x - 3)(x + 5)}\ready. (b) Factorize the numerator: \)2x^2 - 5x - 3 = (2x + 1)(x - 3)\). Factorize the denominator using the difference of two squares: \(4x^2 - 1 = (2x - 1)(2x + 1)\). Simplifying the fraction: \(\frac{(2x + 1)(x - 3)}{(2x - 1)(2x + 1)} = \frac{x - 3}{2x - 1}\). (c) Combining the fractions on the LHS: \(\frac{5(x + 1) + 2(x - 2)}{(x - 2)(x + 1)} = 3 \implies \frac{5x + 5 + 2x - 4}{x^2 - x - 2} = 3 \implies \frac{7x + 1}{x^2 - x - 2} = 3 \implies 7x + 1 = 3(x^2 - x - 2) \implies 7x + 1 = 3x^2 - 3x - 6 \implies 3x^2 - 10x - 7 = 0\). Solving using the quadratic formula: \(x = \frac{10 \pm \sqrt{(-10)^2 - 4(3)(-7)}}{6} = \frac{10 \pm \sqrt{184}}{6}\). Since \(\sqrt{184} \approx 13.565\): \(x_1 = \frac{23.565}{6} \approx 3.93\), and \(x_2 = \frac{-3.565}{6} \approx -0.59\).
Marking scheme
(a) M1 for \(4(x + 5) - 3(2x - 3)\), M1 for common denominator \((2x - 3)(x + 5)\), A1 for numerator \(29 - 2x\), A1 for final correct fraction. (b) M1 for factorizing numerator to \((2x + 1)(x - 3)\), M1 for factorizing denominator to \((2x - 1)(2x + 1)\), M1 for cancelling the common factor \((2x + 1)\), A1 for \(\frac{x - 3}{2x - 1}\). (c) M1 for combining fractions: \(\frac{5(x + 1) + 2(x - 2)}{(x - 2)(x + 1)}\), M1 for multiplying out and getting \(7x + 1 = 3x^2 - 3x - 6\), A1 for \(3x^2 - 10x - 7 = 0\), M1 for correct use of quadratic formula on their quadratic, A1 for both \(x = 3.93\) and \(x = -0.59\).
Question 8 · structured
13 marks
A bag contains 7 blue beads and 5 red beads. Two beads are selected at random without replacement. (a)(i) Find the probability that both beads are blue. [2] (a)(ii) Find the probability that the two beads are different colours. [3] (b) Another bag contains \(n\) green beads and 4 yellow beads. Two beads are selected at random without replacement. The probability that both beads are green is \(\frac{5}{14}\). (i) Show that \(9n^2 - 49n - 60 = 0\). [5] (ii) Solve the equation \(9n^2 - 49n - 60 = 0\) to find the number of green beads in the bag. [3]
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Worked solution
(a)(i) Probability both blue: \(P(BB) = \frac{7}{12} \times \frac{6}{11} = \frac{42}{132} = \frac{7}{22}\). (a)(ii) Probability of different colours: \(P(BR) + P(RB) = \left(\frac{7}{12} \times \frac{5}{11}\right) + \left(\frac{5}{12} \times \frac{7}{11}\right) = \frac{35}{132} + \frac{35}{132} = \frac{70}{132} = \frac{35}{66}\). (b)(i) Total beads in the second bag is \(n + 4\). The probability of selecting two green beads without replacement is \(\frac{n}{n + 4} \times \frac{n - 1}{n + 3} = \frac{5}{14}\). Expanding this equation: \(\frac{n^2 - n}{n^2 + 7n + 12} = \frac{5}{14} \implies 14(n^2 - n) = 5(n^2 + 7n + 12) \implies 14n^2 - 14n = 5n^2 + 35n + 60 \implies 9n^2 - 49n - 60 = 0\). (b)(ii) Solve the quadratic equation by factorizing: \(9n^2 - 49n - 60 = 0 \implies (9n + 10)(n - 6) = 0\). Thus, \(n = -10/9\) or \(n = 6\). Since the number of beads must be a positive integer, there are 6 green beads in the bag.
Marking scheme
(a)(i) M1 for \(\frac{7}{12} \times \frac{6}{11}\), A1 for \(\frac{7}{22}\). (a)(ii) M1 for \(\frac{7}{12} \times \frac{5}{11}\) or \(\frac{5}{12} \times \frac{7}{11}\), M1 for adding both cases, A1 for \(\frac{35}{66}\). (b)(i) M1 for total number of beads expressed as \(n + 4\), M1 for product of probabilities \(\frac{n}{n+4} \times \frac{n-1}{n+3}\), M1 for setting product equal to \(\frac{5}{14}\), M1 for clearing denominators: \(14(n^2 - n) = 5(n^2 + 7n + 12)\), A1 for correctly expanding and simplifying to \(9n^2 - 49n - 60 = 0\). (b)(ii) M1 for factorizing or using quadratic formula, A1 for finding solutions \(6\) and \(-10/9\), A1 for choosing positive integer \(n = 6\).
Question 9 · structured
13 marks
A cyclist rides a distance of 36 km at an average speed of \(x\) km/h.
(a) Write down an expression, in terms of \(x\), for the time taken in hours. [1]
(b) On the return journey, the cyclist is tired and the average speed is reduced by 3 km/h. Write down an expression, in terms of \(x\), for the time taken in hours for the return journey. [1]
(c) The total time for the outward and return journey is 5.5 hours. (i) Show that \(11x^2 - 177x + 216 = 0\). [4] (ii) Solve the equation \(11x^2 - 177x + 216 = 0\). Show all your working and give your answers correct to 2 decimal places. [4]
(d) Find the time taken, in hours and minutes, for the return journey. Give your answer correct to the nearest minute. [3]
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(d) For the return journey, the speed must be positive: \(x - 3 > 0 \implies x > 3\). Therefore, we use the valid solution \(x \approx 14.76058\). The speed for the return journey is: \(14.76058 - 3 = 11.76058\) km/h. Time taken = \(\frac{36}{11.76058} \approx 3.06107\) hours. Converting the fractional part to minutes: \(0.06107 \times 60 \approx 3.66\) minutes. To the nearest minute, this is 4 minutes. So, the time taken is 3 hours 4 minutes.
Marking scheme
(a) B1 for \(\frac{36}{x}\) (b) B1 for \(\frac{36}{x-3}\) (c)(i) M1 for \(\frac{36}{x} + \frac{36}{x-3} = 5.5\) (or equivalent) M1 for eliminating denominators correctly, e.g., \(36(x-3) + 36x = 5.5x(x-3)\) M1 for expanding brackets correctly, e.g., \(36x - 108 + 36x = 5.5x^2 - 16.5x\) A1 for fully correct working leading to the target equation \(11x^2 - 177x + 216 = 0\) (c)(ii) M1 for correct substitution into quadratic formula, e.g., \(\frac{177 \pm \sqrt{(-177)^2 - 4(11)(216)}}{2 \times 11}\) (condone one sign error) B1 for \(21825\) inside the square root (or \(147.7...\)) A1 for \(14.76\) (accept 14.760 to 14.761) A1 for \(1.33\) (accept 1.330 to 1.331) (d) M1 for choosing \(x \approx 14.76\) and calculating return speed \(x - 3\) (approx. \(11.76\)) M1 for calculating \(\frac{36}{\text{their speed}}\) (approx. \(3.06\) hours) and attempting to convert decimal hours to minutes A1 for 3 hours 4 minutes
Question 10 · structured
13 marks
A hiker starts at camp \(A\) and walks 8 km on a bearing of \(040^\circ\) to point \(B\). The hiker then walks 12 km on a bearing of \(115^\circ\) to point \(C\).
(a) Find the distance \(AC\). [4]
(b) Find the bearing of \(C\) from \(A\). [5]
(c) The hiker walks directly back from \(C\) to \(A\) at an average speed of 4.5 km/h. Find the time taken, in hours and minutes, correct to the nearest minute. [2]
(d) Calculate the area of the triangle \(ABC\). [2]
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Worked solution
(a) Let us find the angle \(ABC\). The bearing of \(B\) from \(A\) is \(040^\circ\). The back-bearing from \(B\) to \(A\) is \(040^\circ + 180^\circ = 220^\circ\). The bearing of \(C\) from \(B\) is \(115^\circ\). Therefore, the angle \(ABC\) is the difference between these two bearings: \(\angle ABC = 220^\circ - 115^\circ = 105^\circ\).
Using the cosine rule on triangle \(ABC\): \(AC^2 = AB^2 + BC^2 - 2(AB)(BC)\cos(\angle ABC)\) \(AC^2 = 8^2 + 12^2 - 2(8)(12)\cos(105^\circ)\) \(AC^2 = 64 + 144 - 192\cos(105^\circ)\) \(AC^2 \approx 208 - 192(-0.258819)\) \(AC^2 \approx 208 + 49.693\) \(AC^2 \approx 257.693\) \(AC = \sqrt{257.693} \approx 16.0528\) km. To 3 significant figures, \(AC = 16.1\) km.
(b) To find the bearing of \(C\) from \(A\), we first find the angle \(BAC\) (let us call it \(\theta\)). Using the sine rule: \(\frac{\sin\theta}{12} = \frac{\sin(105^\circ)}{16.0528}\) \(\sin\theta = 12 \times \frac{\sin(105^\circ)}{16.0528}\) \(\sin\theta \approx 12 \times 0.060172 \approx 0.72206\) \(\theta = \sin^{-1}(0.72206) \approx 46.226^\circ\).
The bearing of \(B\) from \(A\) is \(040^\circ\). Since point \(C\) lies in a clockwise direction relative to the line \(AB\) from \(A\), the bearing of \(C\) from \(A\) is: \(\text{Bearing} = 40^\circ + 46.226^\circ = 086.226^\circ\). To 1 decimal place, the bearing is \(086.2^\circ\).
(c) The distance from \(C\) to \(A\) is \(16.0528\) km. Speed = \(4.5\) km/h. \(\text{Time} = \frac{16.0528}{4.5} \approx 3.5673\) hours. Converting the decimal part to minutes: \(0.5673 \times 60 \approx 34.04\) minutes. To the nearest minute, this is 34 minutes. So, the time taken is 3 hours 34 minutes.
(d) Area of triangle \(ABC\): \(\text{Area} = \frac{1}{2} \times AB \times BC \times \sin(\angle ABC)\) \(\text{Area} = \frac{1}{2} \times 8 \times 12 \times \sin(105^\circ)\) \(\text{Area} = 48 \times \sin(105^\circ) \approx 46.364\) \(\text{km}^2\). To 3 significant figures, the area is \(46.4\) \(\text{km}^2\).
Marking scheme
(a) M1 for calculating angle \(ABC = 105^\circ\) (may be shown on a sketch) M1 for substituting correctly into the Cosine Rule: \(8^2 + 12^2 - 2(8)(12)\cos(105)\) A1 for \(257.7\) or \(16.05...\) A1 for \(16.1\) (or \(16.05\) to \(16.06\))
(b) M1 for correct use of Sine Rule or Cosine Rule to find angle \(BAC\), e.g., \(\frac{\sin(BAC)}{12} = \frac{\sin(105)}{\text{their } AC}\) M1 for correct rearrangement to find \(\sin(BAC)\) or \(\cos(BAC)\) A1 for angle \(BAC = 46.2^\circ\) (accept \(46.2^\circ\) to \(46.3^\circ\)) M1 for adding \(40^\circ\) to their angle \(BAC\) A1 for \(086.2^\circ\) or \(086.3^\circ\) (accept \(86.2\) or \(86.3\))
(c) M1 for \(\frac{\text{their } AC}{4.5}\) (approx. \(3.57\) hours) A1 for 3 hours 34 minutes (accept 3h 34m)
(d) M1 for \(\frac{1}{2} \times 8 \times 12 \times \sin(105)\) A1 for \(46.4\) (accept \(46.36\) to \(46.4\))
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