CCEA GCSE · thinka-original Practice Paper

2023 CCEA GCSE Mathematics 2210 Practice Paper with Answers

Thinka Nov 2023 CCEA GCSE-Style Mock — Mathematics 2210

100 marks120 mins2023
An original Thinka practice paper modelled on the structure and difficulty of the Nov 2023 CCEA GCSE Mathematics 2210 paper. Not affiliated with or reproduced from CCEA.

Section A: Foundational Higher Tier Core

Answer all questions. Show all working clearly in the spaces provided. Calculator allowed.
8 Question · 25 marks
Question 1 · Scatter graph interpretation and correlation / outlier identification
2 marks
The table shows the revision time, x hours, and the test score, y%, for 8 students.

Hours revised (x): 1 2 3 4 5 6 7 2
Test score % (y): 38 45 52 61 68 75 82 79

(a) Describe the type of correlation shown by the data for the 7 students whose results follow the general trend. [1]
(b) One student's result does not fit the trend shown by the rest of the group. Write down this student's data pair (x, y) and suggest one reason why it might be an outlier. [1]
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Worked solution

(a) As the number of hours revised increases, the test score also increases for 7 of the 8 students (roughly following score ≈ 7x + 31), so this is strong positive correlation.
(b) The point (2, 79) does not fit this trend — a student who revised for only 2 hours would be expected to score around 45%, not 79%. Possible reason: this student may already have known the material well from previous study, extra tuition, or a strong natural aptitude for the subject. Final answer: outlier (2, 79).

Marking scheme

(a) [1] B1: correct description "(strong) positive correlation". (b) [1] B1: correct pair (2, 79) stated, with a sensible contextual reason for the anomaly (e.g. prior knowledge); accept any plausible reason. Reject an answer that just repeats "it's different" with no reason.
Question 2 · Multi-step Pythagoras theorem with unit conversion and rounding up context
5 marks
A radio mast stands vertically on level ground. The mast is 35 m tall. A support cable runs in a straight line from the top of the mast to a point on the ground 50 m from the foot of the mast, so that the mast, the ground and the cable form a right-angled triangle with the right angle at the foot of the mast.

(a) Calculate the length of the cable, giving your answer correct to 2 decimal places. [3]
(b) The cable is sold only in whole-metre lengths. Find the minimum number of complete metres of cable that must be bought. [1]
(c) Give the length found in part (a) in kilometres, correct to 3 significant figures. [1]
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Worked solution

(a) By Pythagoras' theorem: cable² = 35² + 50² = 1225 + 2500 = 3725. Cable = \( \sqrt{3725} = 61.0327...\ \text{m} \approx 61.03 \) m (2 d.p.).
(b) Since only whole metres can be bought and the exact length (61.03 m) must be covered, round UP to 62 m.
(c) \( 61.0327... \div 1000 = 0.0610 \) km (3 s.f.).
Final answer (minimum metres to buy): 62 m.

Marking scheme

(a) [3] M1: 35² + 50² (or equivalent use of Pythagoras); M1: √3725 evaluated; A1: 61.03 m (2 d.p., accept 61.0). (b) [1] B1 ft: correct round-UP of their (a) to next whole metre (62, or ft from their value) — must be rounded up, not to nearest. (c) [1] B1 ft: their (a) ÷ 1000 to 3 s.f., e.g. 0.0610 km.
Question 3 · Geometric area calculation of standard quadrilateral (kite/trapezium)
2 marks
A trapezium has parallel sides of length 8 cm and 14 cm. The perpendicular distance between the parallel sides is 6 cm.

Calculate the area of the trapezium.

Answer ____________ cm² [2]
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Worked solution

Area of trapezium = \( \frac{1}{2}(a+b)h = \frac{1}{2}(8+14)(6) = \frac{1}{2}(22)(6) = 66 \) cm². Final answer: 66 cm².

Marking scheme

[2] M1: correct substitution into \( \frac{1}{2}(a+b)h \); A1: 66 cm² (units required for A1).
Question 4 · Venn diagram reading and multi-category arithmetic
4 marks
In a class of 32 students, 18 study French, 15 study Spanish, and 6 study neither language.

(a) Draw information from this to find the number of students who study both French and Spanish. [2]
(b) A student is chosen at random from the class. Find the probability that the student studies French but not Spanish. Give your answer as a fraction in its simplest form. [2]
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Worked solution

(a) Students studying at least one language = 32 − 6 = 26. Using |F ∪ S| = |F| + |S| − |F ∩ S|: 26 = 18 + 15 − |F ∩ S| = 33 − |F ∩ S|, so |F ∩ S| = 33 − 26 = 7. Both languages: 7 students.
(b) French only = 18 − 7 = 11 students. P(French but not Spanish) = 11/32 (already in simplest form, since 11 is prime and does not divide 32). Final answer: 11/32.

Marking scheme

(a) [2] M1: 32 − 6 = 26 (at least one language) and |F|+|S| = 33 seen; A1: both = 7. (b) [2] M1 ft: French only = 18 − their both; A1 ft: 11/32 (accept equivalent unsimplified fraction with correct numerator/denominator; ft their (a)).
Question 5 · Coordinate geometry: midpoint of line segment
2 marks
A is the point (−3, 7) and B is the point (9, −1).

Find the coordinates of the midpoint of AB.

Answer ( ____ , ____ ) [2]
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Worked solution

Midpoint = \( \left( \frac{-3+9}{2}, \frac{7+(-1)}{2} \right) = \left( \frac{6}{2}, \frac{6}{2} \right) = (3, 3) \). Final answer: (3, 3).

Marking scheme

[2] M1: correct method for at least one coordinate, e.g. \( \frac{-3+9}{2} \); A1: (3, 3), both coordinates correct.
Question 6 · Linear real-life conversion graph interpretation and unit rate / gradient calculation
3 marks
A conversion graph shows the relationship between the volume of petrol used, y litres, and the distance travelled, x km, by a delivery van. The graph is a straight line through the origin, passing through the point (160, 20).

(a) Find the gradient of the line, stating the units of your answer. [2]
(b) Hence state the number of kilometres the van can travel per litre of fuel. [1]
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Worked solution

(a) Gradient \( = \frac{20 - 0}{160 - 0} = \frac{20}{160} = 0.125 \) litres per km.
(b) Distance per litre \( = \frac{1}{0.125} = 8 \) km per litre (equivalently, 160 km ÷ 20 litres = 8 km per litre). Final answer: 8 km per litre.

Marking scheme

(a) [2] M1: \( \frac{20}{160} \); A1: 0.125 litres/km (units required). (b) [1] B1 ft: 8 km per litre (ft as reciprocal of their (a), or independently as 160÷20).
Question 7 · Reverse / successive percentage discount calculation with justification
5 marks
A coat is on sale in a shop's Winter Sale. The sale price, after a 20% discount off the original price, is £68.

(a) Calculate the original price of the coat. [3]
In a further Clearance Sale, the shop reduces this £68 sale price by a further 15%.
(b) A customer claims that applying the two discounts (20% then 15%) one after the other is equivalent to a single overall discount of 35% off the original price. Show whether the customer is correct, giving the actual overall percentage discount. [2]
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Worked solution

(a) £68 represents 80% of the original price P: \( 0.8P = 68 \Rightarrow P = \frac{68}{0.8} = 85 \). Original price = £85.
(b) Final price after both discounts = \( 68 \times 0.85 = 57.80 \). Overall reduction from the original price = \( 85 - 57.80 = 27.20 \). Overall percentage discount \( = \frac{27.20}{85} \times 100\% = 32\% \) (equivalently, combined multiplier \( 0.8 \times 0.85 = 0.68 \), i.e. a 32% reduction, not 35%). The customer is NOT correct; the true combined discount is 32%.

Marking scheme

(a) [3] M1: 0.8P = 68 (or equivalent, e.g. 68 ÷ 0.8); M1: correct rearrangement/method; A1: £85. (b) [2] M1: 68 × 0.85 (= 57.80) or combined multiplier 0.8 × 0.85 = 0.68; A1: correct conclusion that combined discount is 32%, not 35%, with the value 32% stated. No credit for stating 35% is correct.
Question 8 · Two-step linear fractional equation solution
2 marks
Solve the equation \( \frac{x}{4} + 3 = 8 \).

Answer x = ____________ [2]
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Worked solution

\( \frac{x}{4} + 3 = 8 \Rightarrow \frac{x}{4} = 5 \Rightarrow x = 20 \). Final answer: x = 20.

Marking scheme

[2] M1: \( \frac{x}{4} = 5 \) (subtracting 3 from both sides); A1: x = 20.

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Section B: Intermediate Higher Tier Skills

Answer all questions. Show all working clearly. Give answers to specified accuracy.
9 Question · 30 marks
Question 1 · Prime factor decomposition for Lowest Common Multiple (LCM)
3 marks
(a) Write 84 and 126 as products of their prime factors. [2]
(b) Hence find the lowest common multiple (LCM) of 84 and 126. [1]
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Worked solution

(a) \( 84 = 2^2 \times 3 \times 7 \); \( 126 = 2 \times 3^2 \times 7 \).
(b) LCM uses the highest power of each prime present: \( 2^2 \times 3^2 \times 7 = 4 \times 9 \times 7 = 252 \). Final answer: 252.

Marking scheme

(a) [2] B1: \( 84 = 2^2 \times 3 \times 7 \); B1: \( 126 = 2 \times 3^2 \times 7 \). (b) [1] B1 ft: 252, using highest power of each prime from their (a).
Question 2 · Forming and solving quadratic equation from geometric area
3 marks
A rectangle has width \( x \) cm and length \( (x + 5) \) cm. The area of the rectangle is 84 cm².

(a) Show that \( x^2 + 5x - 84 = 0 \). [1]
(b) Solve the equation to find the width of the rectangle. [2]
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Worked solution

(a) Area = length × width: \( x(x+5) = 84 \Rightarrow x^2 + 5x = 84 \Rightarrow x^2 + 5x - 84 = 0 \).
(b) Factorising: need two numbers multiplying to −84 and summing to 5: 12 and −7. \( (x+12)(x-7) = 0 \Rightarrow x = -12 \) or \( x = 7 \). Since \( x \) is a width, \( x > 0 \), so \( x = -12 \) is rejected. Final answer: x = 7 cm (length = 12 cm, check: 7 × 12 = 84 ✓).

Marking scheme

(a) [1] B1: correct expansion/rearrangement shown to the given equation. (b) [2] M1: correct factorisation (x+12)(x-7) or use of the quadratic formula; A1: x = 7, with x = −12 explicitly rejected as not a valid width.
Question 3 · Simplifying algebraic fractions by common denominator addition
3 marks
Write \( \frac{3}{x+2} + \frac{2}{x-1} \) as a single fraction in its simplest form.
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Worked solution

Common denominator is \( (x+2)(x-1) \): \( \frac{3(x-1)}{(x+2)(x-1)} + \frac{2(x+2)}{(x+2)(x-1)} = \frac{3(x-1) + 2(x+2)}{(x+2)(x-1)} \). Expanding the numerator: \( 3x - 3 + 2x + 4 = 5x + 1 \). Final answer: \( \frac{5x+1}{(x+2)(x-1)} \) (equivalently \( \frac{5x+1}{x^2+x-2} \)).

Marking scheme

[3] M1: correct common denominator (x+2)(x-1); M1: correct numerator 3(x-1) + 2(x+2) formed; A1: simplified to \( \frac{5x+1}{(x+2)(x-1)} \) — no further common factor to cancel.
Question 4 · Linear equations of parallel and intersecting straight lines (y = mx + c)
4 marks
Line \( L_1 \) passes through the points (1, 4) and (3, 10).

(a) Find the equation of \( L_1 \) in the form \( y = mx + c \). [2]
Line \( L_2 \) is parallel to \( L_1 \) and passes through the point (0, −2).
(b) Find the equation of \( L_2 \), and determine whether the point (5, 13) lies on \( L_2 \). [2]
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Worked solution

(a) Gradient of \( L_1 = \frac{10-4}{3-1} = \frac{6}{2} = 3 \). Using (1,4): \( 4 = 3(1) + c \Rightarrow c = 1 \). So \( L_1: y = 3x + 1 \).
(b) Parallel lines have equal gradient, so \( L_2 \) has gradient 3. Through (0,−2): \( c = -2 \), so \( L_2: y = 3x - 2 \). Testing (5,13): \( 3(5) - 2 = 15 - 2 = 13 \), which matches the y-coordinate, so (5, 13) DOES lie on \( L_2 \). Final answer: L2: y = 3x − 2; yes, (5,13) lies on L2.

Marking scheme

(a) [2] M1: gradient = 3 found; A1: y = 3x + 1. (b) [2] M1 ft: y = 3x − 2 stated (gradient ft from (a)); A1: correct substitution showing 3(5) − 2 = 13 and correct conclusion that the point lies on the line.
Question 5 · Compound measures: pressure/force/area with unit specification
3 marks
A force of 450 N acts on a surface of area 0.36 m².

(a) Calculate the pressure exerted on the surface, giving your answer in N/m² (pascals). [2]
(b) Give your answer to part (a) in kilopascals (kPa). [1]
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Worked solution

(a) Pressure = Force ÷ Area = \( \frac{450}{0.36} = 1250 \) N/m² (Pa).
(b) \( 1250 \text{ Pa} \div 1000 = 1.25 \) kPa. Final answer: 1.25 kPa.

Marking scheme

(a) [2] M1: 450 ÷ 0.36; A1: 1250 Pa (units required). (b) [1] B1 ft: their (a) ÷ 1000, e.g. 1.25 kPa.
Question 6 · Area of circle sector in practical context
3 marks
A garden sprinkler waters a sector of a circular lawn of radius 8 m. The sector has an angle of 75° at the centre.

Calculate the area of lawn watered by the sprinkler, giving your answer correct to 3 significant figures.
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Worked solution

Area of sector \( = \frac{\theta}{360} \times \pi r^2 = \frac{75}{360} \times \pi \times 8^2 = \frac{75}{360} \times \pi \times 64 = 41.887... \) m². Rounded to 3 s.f.: 41.9 m². Final answer: 41.9 m².

Marking scheme

[3] M1: \( \frac{75}{360} \times \pi \times 8^2 \) — correct substitution; M1: correct method/evaluation; A1: 41.9 m² (3 s.f., units required).
Question 7 · Interquartile range and choosing representative average in skewed data
4 marks
The overtime hours worked in one week by 15 employees, listed in order, were:

2, 2, 3, 3, 4, 4, 5, 5, 6, 7, 8, 9, 10, 12, 25

(a) Find the interquartile range of this data. [2]
(b) The mean of this data is 7 hours and the median is 5 hours. State, with a reason, which of the mean or the median better represents a typical employee's overtime in this data set. [2]
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Worked solution

(a) With n = 15 values in order, the lower quartile is the \( \frac{1}{4}(n+1) = 4\text{th} \) value = 3, and the upper quartile is the \( \frac{3}{4}(n+1) = 12\text{th} \) value = 9. IQR = 9 − 3 = 6 hours.
(b) The value 25 is a clear outlier compared with the rest of the data (which lie between 2 and 12), and this outlier pulls the mean (7) noticeably above the median (5). Because the median is not affected by extreme values, the median (5 hours) better represents a typical employee's overtime. Final answer: IQR = 6 hours; median is the more representative average.

Marking scheme

(a) [2] M1: correct identification of Q1 = 3 and Q3 = 9 (or equivalent valid quartile method); A1: IQR = 6. (b) [2] B1: median selected; B1: correct reason referring to the outlier (25) distorting the mean / median unaffected by extreme values. No credit for "median" with no valid reason.
Question 8 · Cumulative frequency curve reading: median and pass rates
3 marks
The cumulative frequency table below shows the marks (out of 80) obtained by 60 students in a test.

Mark ≤ 20 : cumulative frequency 6
Mark ≤ 40 : cumulative frequency 22
Mark ≤ 50 : cumulative frequency 40
Mark ≤ 60 : cumulative frequency 52
Mark ≤ 70 : cumulative frequency 58
Mark ≤ 80 : cumulative frequency 60

(a) Using linear interpolation within the 40–50 class, estimate the median mark. Give your answer correct to 1 decimal place. [2]
(b) The pass mark for the test was 40. Estimate the percentage of students who passed. [1]
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Worked solution

(a) The median is the \( \frac{60}{2} = 30\text{th} \) value. This lies in the 40–50 class (cumulative frequency rises from 22 to 40 across this class of 18 students). Median \( \approx 40 + \frac{30-22}{40-22} \times 10 = 40 + \frac{8}{18} \times 10 = 40 + 4.44... = 44.4 \) marks (1 d.p.).
(b) Number scoring below the pass mark (40) = 22 (cumulative frequency at 40). Number passing = 60 − 22 = 38. Percentage passing \( = \frac{38}{60} \times 100\% = 63.3\% \) (1 d.p.). Final answer: median ≈ 44.4 marks; 63.3% passed.

Marking scheme

(a) [2] M1: correct interpolation set-up \( 40 + \frac{30-22}{18} \times 10 \); A1: 44.4 (1 d.p., accept 44.4–44.5 range from sensible graph reading). (b) [1] B1 ft: 38/60 × 100 = 63.3% (ft from their reading of cf at mark 40).
Question 9 · Stratified sampling explanation and group size calculations
4 marks
A school has 180 Year 10 students and 150 Year 11 students. A sample of 55 students is to be chosen using stratified sampling by year group.

(a) Explain what is meant by a stratified sample. [1]
(b) Calculate the number of Year 10 students and the number of Year 11 students that should be included in the sample. [3]
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Worked solution

(a) A stratified sample divides the population into groups (strata) — here, Year 10 and Year 11 — and selects a sample from each group in proportion to the size of that group within the whole population, usually then chosen at random within each stratum.
(b) Total students = 180 + 150 = 330. Year 10 in sample \( = 55 \times \frac{180}{330} = 55 \times \frac{6}{11} = 30 \). Year 11 in sample \( = 55 \times \frac{150}{330} = 55 \times \frac{5}{11} = 25 \). Check: 30 + 25 = 55 ✓. Final answer: 30 Year 10 students, 25 Year 11 students.

Marking scheme

(a) [1] B1: correct explanation referencing proportional representation of each stratum/group. (b) [3] M1: 330 total students identified; M1: correct method \( 55 \times \frac{180}{330} \) (or equivalent) for at least one group; A1: 30 and 25 both correct, summing to 55.

Section C: Advanced Grade A/A* Problems

Answer all questions. Full algebraic working and mathematical reasoning required.
9 Question · 45 marks
Question 1 · Compound right-angled triangle trigonometry involving shared sides
4 marks
ABC and ACD are two right-angled triangles that share the side AC (diagram not drawn to scale). Angle ABC = 90°, AB = 12 cm and BC = 9 cm. Angle ACD = 90° and angle ADC = 32°.

Calculate the length of CD, giving your answer correct to 3 significant figures.
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Worked solution

First find AC using Pythagoras in triangle ABC: \( AC = \sqrt{AB^2 + BC^2} = \sqrt{12^2 + 9^2} = \sqrt{144+81} = \sqrt{225} = 15 \) cm.
In triangle ACD, the right angle is at C, angle ADC = 32°, and AC = 15 cm is the side opposite angle ADC. CD is adjacent to angle ADC, so \( \tan(32°) = \frac{AC}{CD} \Rightarrow CD = \frac{15}{\tan(32°)} = \frac{15}{0.6249} = 24.005... \) cm. Rounded to 3 s.f.: 24.0 cm. Final answer: CD = 24.0 cm.

Marking scheme

[4] M1: AC² = 12² + 9² (Pythagoras set up in triangle ABC); A1: AC = 15 cm; M1: correct trig ratio set up in triangle ACD, \( CD = \frac{15}{\tan 32°} \) (ft their AC); A1: CD = 24.0 cm (3 s.f., ft their AC).
Question 2 · Algebraic surface area formulation and volume calculation of open 3D prism
7 marks
An open-topped water trough is in the shape of a cuboid with no top face. The rectangular base has length \( 3x \) cm and width \( x \) cm. The height of the trough is \( (x-2) \) cm.

(a) Show that the total surface area of the trough (the base and the four vertical sides, with no top) is given by \( A = 11x^2 - 16x \) cm². [4]
(b) Given that \( x = 6 \), calculate the volume of the trough. [3]
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Worked solution

(a) Base area \( = 3x \times x = 3x^2 \). The two long side walls each have area \( 3x \times (x-2) \), giving \( 2 \times 3x(x-2) = 6x^2 - 12x \). The two end walls each have area \( x \times (x-2) \), giving \( 2x(x-2) = 2x^2 - 4x \). Total: \( A = 3x^2 + (6x^2-12x) + (2x^2-4x) = 11x^2 - 16x \) cm², as required.
(b) At \( x = 6 \): base area \( = 3(6)(6) = 108 \) cm²; height \( = 6 - 2 = 4 \) cm. Volume = base area × height \( = 108 \times 4 = 432 \) cm³. Final answer: 432 cm³.

Marking scheme

(a) [4] M1: base area 3x²; M1: two side walls 6x² − 12x; M1: two end walls 2x² − 4x; A1: correctly summed to 11x² − 16x (all terms shown, no errors). (b) [3] M1: base area at x=6 = 108 cm²; M1: height = 4 cm; A1: volume = 432 cm³ (units required).
Question 3 · Upper and lower bounds division problem
3 marks
A car travels a distance of 340 km, measured to the nearest 10 km, in a time of 5.2 hours, measured to the nearest 0.1 hours.

Calculate the upper bound for the car's average speed, giving your answer correct to 1 decimal place.
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Worked solution

Upper bound of distance = 340 + 5 = 345 km. Lower bound of time = 5.2 − 0.05 = 5.15 hours. To maximise speed (= distance ÷ time), use the largest possible distance with the smallest possible time: \( \text{speed}_{max} = \frac{345}{5.15} = 66.990... \) km/h. Rounded to 1 d.p.: 67.0 km/h. Final answer: 67.0 km/h.

Marking scheme

[3] B1: upper bound of distance = 345 km; B1: lower bound of time = 5.15 hours; A1: 345 ÷ 5.15 = 67.0 km/h (1 d.p.) — no credit for using upper bound of time or lower bound of distance.
Question 4 · Circle theorem angle problem requiring written geometric justifications
6 marks
A, B, C and D are four points on a circle, in that order, with centre O. AC is a diameter of the circle. Angle CAB = 40° and angle ACD = 25°.

(a) Find the size of angle ABC, giving a reason for your answer. [2]
(b) Find the size of angle ADC, giving a reason for your answer. [2]
(c) Find the size of angle BAD. [2]
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Worked solution

(a) Angle ABC = 90°, because the angle in a semicircle (subtended by the diameter AC) is always 90°.
(b) ABCD is a cyclic quadrilateral, and opposite angles of a cyclic quadrilateral sum to 180°. So angle ADC = 180° − angle ABC = 180° − 90° = 90°.
(c) In triangle ACD, the angles sum to 180°: angle CAD = 180° − angle ADC − angle ACD = 180° − 90° − 25° = 65°. Angle BAD = angle BAC + angle CAD = 40° + 65° = 105°. Final answer: angle BAD = 105°.

Marking scheme

(a) [2] MA1: angle ABC = 90°; MA1: reason "angle in a semicircle is 90°". (b) [2] MA1 ft: angle ADC = 90° (ft their (a)); MA1: reason "opposite angles of a cyclic quadrilateral sum to 180°". (c) [2] M1: angle CAD = 180 − 90 − 25 = 65° found (ft their (b)); A1: angle BAD = 40 + 65 = 105°.
Question 5 · Multivariate non-monic quadratic factorisation with common factor
3 marks
Factorise fully \( 6x^3 - 5x^2y - 6xy^2 \).
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Worked solution

First take out the common factor x: \( 6x^3 - 5x^2y - 6xy^2 = x(6x^2 - 5xy - 6y^2) \). Now factorise the quadratic \( 6x^2 - 5xy - 6y^2 \): looking for factors of the form \( (3x + ay)(2x + by) \) where \( ab = -6 \) and \( 3b + 2a = -5 \); taking \( a = 2, b = -3 \) gives \( (3x+2y)(2x-3y) \). Check: \( 6x^2 - 9xy + 4xy - 6y^2 = 6x^2 - 5xy - 6y^2 \) ✓. Final answer: \( x(3x+2y)(2x-3y) \).

Marking scheme

[3] B1: common factor x taken out correctly, x(6x² − 5xy − 6y²); M1: correct method to factorise the resulting quadratic (e.g. trial factors checked by expansion); A1: fully correct x(3x+2y)(2x−3y).
Question 6 · Algebraic fractions equation with linear denominators solved by quadratic formula
7 marks
Solve the equation \( \frac{4}{x+1} + \frac{3}{x-2} = 2 \), giving your answers correct to 2 decimal places.
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Worked solution

Multiply both sides by \( (x+1)(x-2) \): \( 4(x-2) + 3(x+1) = 2(x+1)(x-2) \).
LHS: \( 4x - 8 + 3x + 3 = 7x - 5 \).
RHS: \( 2(x^2 - x - 2) = 2x^2 - 2x - 4 \).
So \( 7x - 5 = 2x^2 - 2x - 4 \Rightarrow 0 = 2x^2 - 2x - 4 - 7x + 5 = 2x^2 - 9x + 1 \).
Using the quadratic formula with a=2, b=−9, c=1: \( x = \frac{9 \pm \sqrt{(-9)^2 - 4(2)(1)}}{2(2)} = \frac{9 \pm \sqrt{81-8}}{4} = \frac{9 \pm \sqrt{73}}{4} \).
\( \sqrt{73} = 8.544...\). \( x = \frac{9+8.544}{4} = 4.386 \approx 4.39 \), or \( x = \frac{9-8.544}{4} = 0.114 \approx 0.11 \). Neither value equals −1 or 2, so both are valid. Final answer: x = 4.39 or x = 0.11 (2 d.p.).

Marking scheme

[7] M1: multiplying through by (x+1)(x−2); M1: correct LHS expansion 7x−5; M1: correct RHS expansion 2x²−2x−4; A1: correctly rearranged to 2x²−9x+1=0; M1: correct substitution into the quadratic formula; A1: x = 4.39; A1: x = 0.11 (both required, 2 d.p.).
Question 7 · Histogram analysis: frequency density scaling and median estimation
6 marks
The grouped frequency table shows the times, in minutes, taken by 90 runners to complete a fun run.

Time (min) Frequency
20 – 30 9
30 – 35 15
35 – 40 24
40 – 50 30
50 – 70 12

(a) Calculate the frequency density for the classes 20–30 and 50–70 minutes. [2]
(b) Explain why frequency density, rather than frequency, should be plotted on the vertical axis of a histogram when class widths are unequal. [1]
(c) Using the frequency table, estimate the median time, correct to 1 decimal place. [3]
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Worked solution

(a) Frequency density = frequency ÷ class width. 20–30 (width 10): \( 9 \div 10 = 0.9 \). 50–70 (width 20): \( 12 \div 20 = 0.6 \).
(b) If frequency itself were plotted for classes of unequal width, wider classes would appear to have disproportionately tall bars even if the data is not more densely packed; frequency density (frequency ÷ width) accounts for the different widths so that the AREA of each bar, not its height, represents the frequency — giving a fair visual comparison.
(c) Cumulative frequencies: 9 (≤30), 24 (≤35), 48 (≤40), 78 (≤50), 90 (≤70). The median is the \( \frac{90}{2}=45\text{th} \) value, which falls in the 35–40 class (cumulative frequency rises from 24 to 48 across this class of 24 runners). Median \( \approx 35 + \frac{45-24}{48-24} \times 5 = 35 + \frac{21}{24} \times 5 = 35 + 4.375 = 39.375 \approx 39.4 \) minutes (1 d.p.). Final answer: densities 0.9 and 0.6; median ≈ 39.4 minutes.

Marking scheme

(a) [2] B1: 0.9; B1: 0.6 (both with correct working frequency ÷ width). (b) [1] B1: correct explanation referencing area representing frequency / fair comparison across unequal widths. (c) [3] M1: correct cumulative frequencies built and 45th value located in 35–40 class; M1: correct interpolation set-up \( 35 + \frac{45-24}{24} \times 5 \); A1: 39.4 minutes (1 d.p., accept 39.3–39.5 range).
Question 8 · Simplifying rational expressions involving difference of two squares and common factors
3 marks
Simplify fully \( \frac{x^2-16}{2x^2+9x+4} \).
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Worked solution

Numerator (difference of two squares): \( x^2 - 16 = (x-4)(x+4) \).
Denominator: \( 2x^2 + 9x + 4 = (2x+1)(x+4) \) — check: \( 2x^2 + 8x + x + 4 = 2x^2 + 9x + 4 \) ✓.
So \( \frac{(x-4)(x+4)}{(2x+1)(x+4)} = \frac{x-4}{2x+1} \), cancelling the common factor (x+4) (valid for x ≠ −4). Final answer: \( \frac{x-4}{2x+1} \).

Marking scheme

[3] B1: numerator correctly factorised (x−4)(x+4); M1: denominator correctly factorised (2x+1)(x+4); A1: correctly cancelled to \( \frac{x-4}{2x+1} \).
Question 9 · Solid cone and hemisphere equal total surface area equating and exact/decimal radius solving
6 marks
A solid cone has base radius r cm and slant height \( (r+8) \) cm. A solid hemisphere has the same radius r cm as the cone. The total surface area of the cone is equal to the total surface area of the hemisphere.

(a) Show that \( 2\pi r^2 + 8\pi r = 3\pi r^2 \), and hence show that r = 8. [4]
(b) State the total surface area of the hemisphere, giving your answer first as an exact multiple of π, and then correct to 3 significant figures. [2]
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Worked solution

(a) Total surface area of the cone = curved surface + base = \( \pi r l + \pi r^2 = \pi r(r+8) + \pi r^2 = \pi r^2 + 8\pi r + \pi r^2 = 2\pi r^2 + 8\pi r \).
Total surface area of the hemisphere = curved surface + flat circular base = \( 2\pi r^2 + \pi r^2 = 3\pi r^2 \).
Setting the two total surface areas equal: \( 2\pi r^2 + 8\pi r = 3\pi r^2 \). Dividing both sides by \( \pi r \) (valid since r > 0): \( 2r + 8 = 3r \Rightarrow r = 8 \), as required.
(b) Hemisphere TSA \( = 3\pi r^2 = 3\pi(8)^2 = 3\pi(64) = 192\pi \) cm² (exact). Numerically: \( 192\pi = 603.19 = 603 \) cm² (3 s.f.). Final answer: r = 8 cm; TSA = 192π cm² ≈ 603 cm².

Marking scheme

(a) [4] M1: cone curved surface area πr(r+8); M1: cone total SA = 2πr² + 8πr; M1: hemisphere TSA = 3πr² stated; A1: equation solved correctly to r = 8 (division by πr shown/implied). (b) [2] B1: exact value 192π cm²; B1 ft: 603 cm² (3 s.f., ft their r).

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