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Thinka Jun 2023 AQA A Level-Style Mock — Mathematics 7357

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An original Thinka practice paper modelled on the structure and difficulty of the Jun 2023 AQA A Level Mathematics 7357 paper. Not affiliated with or reproduced from AQA.

Paper 1: Pure Mathematics

Answer all questions. Entirely pure content; calculator and AQA formulae booklet permitted.
11 PastPaper.question · 100 PastPaper.marks
PastPaper.question 1 · Multiple choice
1 PastPaper.marks
Differentiate \(y=\ln(5x)\). Circle your answer.
  1. A.\(\tfrac5x\)
  2. B.\(\tfrac1x\)
  3. C.\(\tfrac{1}{5x}\)
  4. D.\(\ln5\)
PastPaper.showAnswers

PastPaper.workedSolution

\(\tfrac{d}{dx}\ln(5x)=\tfrac{5}{5x}=\tfrac1x\).

PastPaper.markingScheme

B1 for \(\tfrac1x\).
PastPaper.question 2 · Multiple choice
1 PastPaper.marks
Find \(\displaystyle\int e^{3x}\,dx\). Circle your answer.
  1. A.\(3e^{3x}+c\)
  2. B.\(\tfrac13 e^{3x}+c\)
  3. C.\(e^{3x}+c\)
  4. D.\(3e^{x}+c\)
PastPaper.showAnswers

PastPaper.workedSolution

\(\int e^{3x}dx=\tfrac13 e^{3x}+c\).

PastPaper.markingScheme

B1 for \(\tfrac13 e^{3x}+c\).
PastPaper.question 3 · Short
5 PastPaper.marks
Find the first three terms, in ascending powers of \(x\), of the binomial expansion of \((3+2x)^6\).
PastPaper.showAnswers

PastPaper.workedSolution

\((3+2x)^6=3^6+\binom61 3^5(2x)+\binom62 3^4(2x)^2+\dots=729+6(243)(2)x+15(81)(4)x^2=729+2916x+4860x^2\).

PastPaper.markingScheme

M1 binomial structure; A1 729; A1 2916x; M1 third-term values; A1 4860x².
PastPaper.question 4 · Structured
12 PastPaper.marks
A circle \(C\) has equation \(x^2+y^2-10x+2y+1=0\). (a) Find the centre and radius. (b) Show that the point \((5,4)\) lies on \(C\). (c) Find the equation of the tangent to \(C\) at \((5,4)\). (d) Find the length of the tangent to \(C\) from the external point \((12,3)\).
PastPaper.showAnswers

PastPaper.workedSolution

(a) \((x-5)^2+(y+1)^2=25\): centre \((5,-1)\), radius \(5\). (b) \(25+16-50+8+1=0\) ✓. (c) The radius from \((5,-1)\) to \((5,4)\) is vertical, so the tangent is horizontal: \(y=4\). (d) Tangent length \(=\sqrt{(12-5)^2+(3+1)^2-25}=\sqrt{49+16-25}=\sqrt{40}=6.32\).

PastPaper.markingScheme

M1A1 centre & radius; M1A1 (b); M1 radius direction; A1 tangent y=4; M1A1 tangent length.
PastPaper.question 5 · Structured
10 PastPaper.marks
(a) An arithmetic series has first term 4 and common difference 6. Find (i) the 15th term and (ii) the sum of the first 15 terms. (b) A geometric series has first term 4 and common ratio 1.05. Find (i) the 10th term and (ii) the sum of the first 10 terms. (c) State, with a reason, whether the geometric series converges.
PastPaper.showAnswers

PastPaper.workedSolution

(a)(i) \(4+14(6)=88\); (ii) \(S_{15}=\tfrac{15}{2}(8+84)=690\). (b)(i) \(4(1.05)^9=6.20\); (ii) \(S_{10}=4\cdot\tfrac{1.05^{10}-1}{0.05}=50.3\). (c) No: \(|r|=1.05>1\), so it diverges.

PastPaper.markingScheme

M1A1 (a); M1A1 (b)(i); M1A1 (b)(ii); B1 (c) with reason.
PastPaper.question 6 · Structured
12 PastPaper.marks
\(f(x)=x^3-7x+2\). (a) Show that a root of \(f(x)=0\) lies between 2 and 3. (b) Apply the Newton–Raphson method with \(x_0=2.5\) to find \(x_1\) and \(x_2\). (c) The iteration \(x_{n+1}=\sqrt[3]{7x_n-2}\) is used with \(x_0=2.5\). Find the root to 3 decimal places.
PastPaper.showAnswers

PastPaper.workedSolution

(a) \(f(2)=-4<0\), \(f(3)=8>0\): sign change implies a root in \((2,3)\). (b) \(f'(x)=3x^2-7\); \(x_1=2.5-\tfrac{0.125}{11.75}=2.4894\); \(x_2=2.4894-\tfrac{f(2.4894)}{f'(2.4894)}=2.4893\). (c) \(x_1=\sqrt[3]{15.5}=2.494,\,x_2=2.490,\,x_3=2.489,\dots\to 2.489\).

PastPaper.markingScheme

M1 evaluate ends; A1 sign change; M1 NR formula; A1 x₁; A1 x₂; M1 iterate; A1 2.489.
PastPaper.question 7 · Structured
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\(p(x)=2x^3+ax^2+bx-6\). Given that \((x-2)\) and \((x+1)\) are factors: (a) find \(a\) and \(b\); (b) factorise \(p(x)\) completely; (c) solve \(p(x)=0\).
PastPaper.showAnswers

PastPaper.workedSolution

(a) \(p(2)=16+4a+2b-6=0\Rightarrow2a+b=-5\); \(p(-1)=-2+a-b-6=0\Rightarrow a-b=8\). Adding, \(3a=3\Rightarrow a=1,\,b=-7\). (b) \(p(x)=2x^3+x^2-7x-6=(x-2)(x+1)(2x+3)\). (c) \(x=2,-1,-\tfrac32\).

PastPaper.markingScheme

M1 p(2)=0; M1 p(-1)=0; A1 a,b; M1 divide; A1 full factorisation; A1 three roots.
PastPaper.question 8 · Structured
8 PastPaper.marks
(a) A geometric series has first term 6 and common ratio \(\tfrac23\). Find its sum to infinity. (b) Solve \(\tan 2x=1\) for \(0\le x\le\pi\). (c) Solve \(4\sin x=3\cos x\) for \(0\le x\le2\pi\), to 2 decimal places.
PastPaper.showAnswers

PastPaper.workedSolution

(a) \(\tfrac{6}{1-2/3}=18\). (b) \(2x=\tfrac{\pi}{4},\tfrac{5\pi}{4}\Rightarrow x=\tfrac{\pi}{8},\tfrac{5\pi}{8}\). (c) \(\tan x=\tfrac34\Rightarrow x=0.6435\) or \(0.6435+\pi=3.785\).

PastPaper.markingScheme

B1 (a); M1 2x values; A1 both x; M1 tan x; A1 0.64; A1 3.79.
PastPaper.question 9 · Structured
10 PastPaper.marks
(a) Prove the identity \(\dfrac{1+\sin x}{\cos x}+\dfrac{\cos x}{1+\sin x}\equiv\dfrac{2}{\cos x}\). (b) Hence solve \(\dfrac{1+\sin x}{\cos x}+\dfrac{\cos x}{1+\sin x}=4\) for \(0
PastPaper.showAnswers

PastPaper.workedSolution

(a) Common denominator: \(\tfrac{(1+\sin x)^2+\cos^2x}{\cos x(1+\sin x)}=\tfrac{1+2\sin x+\sin^2x+\cos^2x}{\cos x(1+\sin x)}=\tfrac{2+2\sin x}{\cos x(1+\sin x)}=\tfrac{2}{\cos x}\). (b) \(\tfrac{2}{\cos x}=4\Rightarrow\cos x=\tfrac12\Rightarrow x=\tfrac{\pi}{3},\tfrac{5\pi}{3}\). (c) \(\tfrac{1+\cos2x}{\sin2x}=\tfrac{2\cos^2x}{2\sin x\cos x}=\cot x\).

PastPaper.markingScheme

M1 combine; M1 use identity; A1 result; M1A1 (b); M1A1 (c).
PastPaper.question 10 · Structured
15 PastPaper.marks
(a) Find \(\displaystyle\int\left(6x^2-\tfrac{4}{x^2}+e^{3x}\right)dx\). (b) Use the substitution \(u=x^2+4\) to find \(\displaystyle\int\tfrac{2x}{\sqrt{x^2+4}}\,dx\). (c) Find the area enclosed between the curve \(y=x^2+3\) and the line \(y=4x\).
PastPaper.showAnswers

PastPaper.workedSolution

(a) \(2x^3+\tfrac{4}{x}+\tfrac13 e^{3x}+c\). (b) \(u=x^2+4,\,du=2x\,dx\Rightarrow\int u^{-1/2}du=2\sqrt u=2\sqrt{x^2+4}+c\). (c) Intersect: \(x^2+3=4x\Rightarrow x=1,3\); area \(=\int_1^3(4x-x^2-3)dx=[2x^2-\tfrac{x^3}{3}-3x]_1^3=0-(-\tfrac43)=\tfrac43\).

PastPaper.markingScheme

M1A1A1 (a); M1 substitution; A1 (b); M1 limits 1,3; M1 integrate difference; A1 4/3.
PastPaper.question 11 · Structured
16 PastPaper.marks
A curve has equation \(y=2x^3-9x^2+12x-3\). (a) Find \(\dfrac{dy}{dx}\). (b) Find the stationary points and determine their nature. (c) Find the coordinates of the point of inflection. (d) Find the equation of the tangent at \(x=0\). (e) State the set of values of \(x\) for which the curve is increasing.
PastPaper.showAnswers

PastPaper.workedSolution

(a) \(\tfrac{dy}{dx}=6x^2-18x+12=6(x-1)(x-2)\). (b) \(x=1\Rightarrow(1,2)\); \(x=2\Rightarrow(2,1)\). \(\tfrac{d^2y}{dx^2}=12x-18\): at \(x=1\) negative (max), at \(x=2\) positive (min). (c) \(12x-18=0\Rightarrow x=1.5,\,y=1.5\). (d) At \(x=0\), \(y=-3\), gradient \(12\): \(y=12x-3\). (e) Increasing where \(\tfrac{dy}{dx}>0\): \(x<1\) or \(x>2\).

PastPaper.markingScheme

M1A1 derivative; M1 stationary; A1 both; M1A1 natures; M1A1 inflection; M1A1 tangent; B1 increasing set.

Paper 2: Pure & Mechanics

Answer all questions. Section A is pure; Section B is mechanics (take g = 9.8 m s⁻²).
14 PastPaper.question · 100 PastPaper.marks
PastPaper.question 1 · Multiple choice
1 PastPaper.marks
Find \(\displaystyle\int\tfrac1x\,dx\). Circle your answer.
  1. A.\(\ln|x|+c\)
  2. B.\(-\tfrac{1}{x^2}+c\)
  3. C.\(\tfrac{1}{2}x^2+c\)
  4. D.\(x\ln x+c\)
PastPaper.showAnswers

PastPaper.workedSolution

\(\int\tfrac1x dx=\ln|x|+c\).

PastPaper.markingScheme

B1 for \(\ln|x|+c\).
PastPaper.question 2 · Short
3 PastPaper.marks
Express \(\dfrac{4x+5}{(x+1)(x-2)}\) in partial fractions.
PastPaper.showAnswers

PastPaper.workedSolution

Let \(\tfrac{4x+5}{(x+1)(x-2)}=\tfrac{A}{x+1}+\tfrac{B}{x-2}\). Then \(4x+5=A(x-2)+B(x+1)\). \(x=-1:1=-3A\Rightarrow A=-\tfrac13\); \(x=2:13=3B\Rightarrow B=\tfrac{13}{3}\).

PastPaper.markingScheme

M1 set up identity; M1 substitute; A1 A=-1/3, B=13/3.
PastPaper.question 3 · Proof
6 PastPaper.marks
Prove by contradiction that \(\sqrt5\) is irrational.
PastPaper.showAnswers

PastPaper.workedSolution

Assume \(\sqrt5=\tfrac pq\) in lowest terms. Then \(p^2=5q^2\), so \(5\mid p^2\Rightarrow5\mid p\). Write \(p=5k\): \(25k^2=5q^2\Rightarrow q^2=5k^2\), so \(5\mid q\). Then 5 divides both \(p\) and \(q\), contradicting lowest terms. Hence \(\sqrt5\) is irrational.

PastPaper.markingScheme

B1 assume rational; M1 \(p^2=5q^2\); A1 5|p; M1 substitute; A1 5|q; A1 contradiction.
PastPaper.question 4 · Structured
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A closed box has a square base of side \(x\,\text{cm}\) and volume \(1000\,\text{cm}^3\). (a) Show that the total surface area is \(S=2x^2+\dfrac{4000}{x}\). (b) Find the value of \(x\) that minimises \(S\). (c) Find the minimum surface area.
PastPaper.showAnswers

PastPaper.workedSolution

(a) Height \(h=\tfrac{1000}{x^2}\); \(S=2x^2+4xh=2x^2+\tfrac{4000}{x}\). (b) \(\tfrac{dS}{dx}=4x-\tfrac{4000}{x^2}=0\Rightarrow x^3=1000\Rightarrow x=10\). (c) \(S=200+400=600\,\text{cm}^2\) (\(\tfrac{d^2S}{dx^2}>0\), minimum).

PastPaper.markingScheme

M1 height; A1 show S; M1 differentiate; M1 solve =0; A1 x=10; A1 S=600.
PastPaper.question 5 · Structured
10 PastPaper.marks
(a) A population grows so that \(\dfrac{dP}{dt}=0.4P\). Show that \(P=Ae^{0.4t}\). (b) Given \(P=150\) when \(t=0\), find \(P\) when \(t=5\). (c) Solve the differential equation \(\dfrac{dy}{dx}=4x^3y\), giving \(y\) in terms of \(x\).
PastPaper.showAnswers

PastPaper.workedSolution

(a) \(\int\tfrac{dP}{P}=\int0.4\,dt\Rightarrow\ln P=0.4t+c\Rightarrow P=Ae^{0.4t}\). (b) \(A=150\Rightarrow P=150e^{2}=1108\). (c) \(\int\tfrac{dy}{y}=\int4x^3dx\Rightarrow\ln y=x^4+c\Rightarrow y=Be^{x^4}\).

PastPaper.markingScheme

M1 separate; A1 show; M1 A=150; A1 1108; M1 separate; A1 \(y=Be^{x^4}\).
PastPaper.question 6 · Structured
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(a) Solve \(3^{2x}-12\cdot3^{x}+27=0\). (b) Solve \(\log_3 x+\log_3(x+6)=3\). (c) Evaluate \(\log_2 32-\log_2 4\).
PastPaper.showAnswers

PastPaper.workedSolution

(a) Let \(y=3^x\): \(y^2-12y+27=0\Rightarrow(y-3)(y-9)=0\Rightarrow3^x=3\,(x=1)\) or \(3^x=9\,(x=2)\). (b) \(\log_3 x(x+6)=3\Rightarrow x^2+6x=27\Rightarrow(x+9)(x-3)=0\Rightarrow x=3\) (reject \(-9\)). (c) \(5-2=3\).

PastPaper.markingScheme

M1 substitution; A1 both x; M1 combine logs; M1 solve; A1 x=3; A1 (c).
PastPaper.question 7 · Structured
11 PastPaper.marks
(a) Express \(5\sin x-12\cos x\) in the form \(R\sin(x-\alpha)\), \(R>0\), \(0<\alpha<90^\circ\). (b) State the maximum value and the value of \(x\) in \(0\le x\le360^\circ\) at which it occurs. (c) Solve \(5\sin x-12\cos x=6.5\) for \(0\le x\le360^\circ\).
PastPaper.showAnswers

PastPaper.workedSolution

(a) \(R=\sqrt{5^2+12^2}=13\), \(\tan\alpha=\tfrac{12}{5}\Rightarrow\alpha=67.38^\circ\): \(13\sin(x-67.38^\circ)\). (b) Max \(13\) when \(x-67.38^\circ=90^\circ\Rightarrow x=157.4^\circ\). (c) \(\sin(x-67.38^\circ)=0.5\Rightarrow x-67.38^\circ=30^\circ,150^\circ\Rightarrow x=97.4^\circ,217.4^\circ\).

PastPaper.markingScheme

M1 R=13; M1 α; A1 form; M1A1 (b); M1 solve; A1 both x.
PastPaper.question 8 · Multiple choice
1 PastPaper.marks
Find the weight of a particle of mass \(8\,\text{kg}\) (take \(g=9.8\)). Circle your answer.
  1. A.\(8\,\text{N}\)
  2. B.\(0.82\,\text{N}\)
  3. C.\(78.4\,\text{N}\)
  4. D.\(9.8\,\text{N}\)
PastPaper.showAnswers

PastPaper.workedSolution

Weight \(=mg=8\times9.8=78.4\,\text{N}\).

PastPaper.markingScheme

B1 for 78.4 N.
PastPaper.question 9 · Structured
6 PastPaper.marks
A particle moves in a straight line with acceleration \(a=(12t-6)\,\text{m s}^{-2}\) and velocity \(4\,\text{m s}^{-1}\) at \(t=0\). (a) Find \(v\) in terms of \(t\). (b) Find \(v\) when \(t=2\). (c) Find the displacement during the first 2 seconds.
PastPaper.showAnswers

PastPaper.workedSolution

(a) \(v=\int(12t-6)dt=6t^2-6t+C\); \(v(0)=4\Rightarrow C=4\), so \(v=6t^2-6t+4\). (b) \(v(2)=24-12+4=16\). (c) \(s=\int_0^2(6t^2-6t+4)dt=[2t^3-3t^2+4t]_0^2=16-12+8=12\,\text{m}\).

PastPaper.markingScheme

M1 integrate a; A1 v; B1 (b); M1 integrate v; A1 12 m.
PastPaper.question 10 · Structured
9 PastPaper.marks
A particle of mass \(3\,\text{kg}\) lies on a smooth plane inclined at \(30^\circ\). It is connected by a light inextensible string over a smooth pulley at the top of the plane to a mass of \(5\,\text{kg}\) hanging freely. The system is released from rest. (a) Find the acceleration. (b) Find the tension. (c) State one assumption about the string.
PastPaper.showAnswers

PastPaper.workedSolution

For the hanging mass: \(5g-T=5a\). On the plane: \(T-3g\sin30^\circ=3a\). Adding: \(5g-1.5g=8a\Rightarrow a=\tfrac{34.3}{8}=4.29\,\text{m s}^{-2}\). Then \(T=5g-5a=49-21.44=27.6\,\text{N}\). (c) The string is light and inextensible.

PastPaper.markingScheme

M1 hanging-mass equation; M1 on-plane equation; A1 add; A1 a=4.29; M1 T; A1 27.6; B1 assumption.
PastPaper.question 11 · Structured
10 PastPaper.marks
A uniform beam \(AB\) of length \(10\,\text{m}\) and weight \(500\,\text{N}\) rests horizontally on supports at \(A\) and \(B\). A load of \(300\,\text{N}\) is placed \(3\,\text{m}\) from \(A\). (a) Find the reaction at each support. (b) Find how far from \(A\) the load must be placed for the reactions to be equal.
PastPaper.showAnswers

PastPaper.workedSolution

(a) Moments about \(A\): \(R_B(10)=500(5)+300(3)=3400\Rightarrow R_B=340\,\text{N}\); \(R_A=500+300-340=460\,\text{N}\). (b) Equal reactions \(=400\) each: \(400(10)=500(5)+300d\Rightarrow300d=1500\Rightarrow d=5\,\text{m}\).

PastPaper.markingScheme

M1 moments about A; A1 R_B; M1 resolve; A1 R_A; M1 set equal; A1 d=5.
PastPaper.question 12 · Structured
8 PastPaper.marks
A particle has position vector \(\mathbf{r}=(t^2-4t)\mathbf{i}+(t^2-2t)\mathbf{j}\) (\(t\) in seconds). (a) Find its velocity when \(t=1\). (b) Find its speed when \(t=1\). (c) Find the time at which it is moving parallel to \(\mathbf{j}\).
PastPaper.showAnswers

PastPaper.workedSolution

\(\mathbf{v}=(2t-4)\mathbf{i}+(2t-2)\mathbf{j}\). (a) At \(t=1\): \(\mathbf{v}=-2\mathbf{i}+0\mathbf{j}\). (b) Speed \(=\sqrt{(-2)^2+0^2}=2\,\text{m s}^{-1}\). (c) Parallel to \(\mathbf{j}\) when the \(\mathbf{i}\)-component is zero: \(2t-4=0\Rightarrow t=2\).

PastPaper.markingScheme

M1 differentiate; A1 v at t=1; M1A1 speed; M1 set i-comp =0; A1 t=2.
PastPaper.question 13 · Structured
6 PastPaper.marks
A ball is thrown horizontally with speed \(20\,\text{m s}^{-1}\) from a point \(25\,\text{m}\) above horizontal ground (take \(g=9.8\)). (a) Find the time to reach the ground. (b) Find the horizontal distance travelled.
PastPaper.showAnswers

PastPaper.workedSolution

(a) \(25=\tfrac12(9.8)t^2\Rightarrow t^2=5.102\Rightarrow t=2.26\,\text{s}\). (b) \(x=20(2.26)=45.2\,\text{m}\).

PastPaper.markingScheme

M1 vertical equation; A1 t=2.26; M1 horizontal motion; A1 45.2 m; B1 method.
PastPaper.question 14 · Structured
9 PastPaper.marks
A particle \(P\) of mass \(4\,\text{kg}\) lies on a smooth horizontal table. It is connected by a light inextensible string passing over a smooth pulley at the edge of the table to a particle \(Q\) of mass \(6\,\text{kg}\) hanging freely. The system is released from rest. (a) Find the acceleration. (b) Find the tension in the string. (c) State one assumption you have made about the pulley.
PastPaper.showAnswers

PastPaper.workedSolution

For \(Q\): \(6g-T=6a\). For \(P\): \(T=4a\). Adding: \(6g=10a\Rightarrow a=\tfrac{58.8}{10}=5.88\,\text{m s}^{-2}\). Then \(T=4(5.88)=23.52\,\text{N}\). (c) The pulley is smooth, so the tension is the same on both sides of the string.

PastPaper.markingScheme

M1 equation for Q; M1 equation for P; A1 add; A1 a=5.88; M1 T; A1 23.52; B1 assumption.

Paper 3: Pure & Statistics

Answer all questions. Section A is pure; Section B is statistics (Large Data Set context).
13 PastPaper.question · 100 PastPaper.marks
PastPaper.question 1 · Multiple choice
1 PastPaper.marks
State the period of \(y=\sin(2\pi x)\). Circle your answer.
  1. A.\(2\pi\)
  2. B.\(\tfrac12\)
  3. C.\(1\)
  4. D.\(\pi\)
PastPaper.showAnswers

PastPaper.workedSolution

Period \(=\tfrac{2\pi}{2\pi}=1\).

PastPaper.markingScheme

B1 for 1.
PastPaper.question 2 · Structured
10 PastPaper.marks
Differentiate each of the following. (a) \(y=(3x-2)^4\). (b) \(y=x^2\ln x\). (c) \(y=\dfrac{x}{x^2+4}\). (d) Hence state the gradient of the curve in part (a) at \(x=1\).
PastPaper.showAnswers

PastPaper.workedSolution

(a) Chain rule: \(12(3x-2)^3\). (b) Product rule: \(2x\ln x+x\). (c) Quotient rule: \(\tfrac{(x^2+4)-x(2x)}{(x^2+4)^2}=\tfrac{4-x^2}{(x^2+4)^2}\). (d) At \(x=1\): \(12(1)^3=12\).

PastPaper.markingScheme

M1A1 (a); M1A1 (b); M1A1 (c); M1A1 (d).
PastPaper.question 3 · Structured
9 PastPaper.marks
Find each integral. (a) \(\displaystyle\int(2x+5)^3\,dx\). (b) \(\displaystyle\int\tfrac{9}{3x+1}\,dx\). (c) \(\displaystyle\int_1^2\tfrac{6}{x^2}\,dx\).
PastPaper.showAnswers

PastPaper.workedSolution

(a) \(\tfrac{(2x+5)^4}{8}+c\). (b) \(3\ln|3x+1|+c\). (c) \([-\tfrac{6}{x}]_1^2=-3-(-6)=3\).

PastPaper.markingScheme

M1A1 (a); M1A1 (b); M1 antiderivative; A1 (c)=3.
PastPaper.question 4 · Structured
10 PastPaper.marks
(a) Solve \(2\cos 2x=\sqrt3\) for \(0\le x\le2\pi\). (b) Prove that \(\tan^2 x+1\equiv\sec^2 x\). (c) Solve \(2\sin x+1=0\) for \(0\le x\le2\pi\).
PastPaper.showAnswers

PastPaper.workedSolution

(a) \(\cos2x=\tfrac{\sqrt3}{2}\Rightarrow2x=\tfrac{\pi}{6},\tfrac{11\pi}{6},\tfrac{13\pi}{6},\tfrac{23\pi}{6}\Rightarrow x=\tfrac{\pi}{12},\tfrac{11\pi}{12},\tfrac{13\pi}{12},\tfrac{23\pi}{12}\). (b) \(\tan^2x+1=\tfrac{\sin^2x}{\cos^2x}+1=\tfrac{\sin^2x+\cos^2x}{\cos^2x}=\tfrac{1}{\cos^2x}=\sec^2x\). (c) \(\sin x=-\tfrac12\Rightarrow x=\tfrac{7\pi}{6},\tfrac{11\pi}{6}\).

PastPaper.markingScheme

M1 cos2x value; A1 all four x; M1A1 (b); M1A1 (c).
PastPaper.question 5 · Structured
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A radioactive sample decays as \(m=m_0e^{-kt}\), with a half-life of 12 years. (a) Find \(k\) to 3 significant figures. (b) Given \(m_0=80\,\text{g}\), find the mass after 20 years. (c) Find, to the nearest year, the time to fall to \(20\,\text{g}\). (d) Find the rate of decay at \(t=0\).
PastPaper.showAnswers

PastPaper.workedSolution

(a) \(e^{-12k}=\tfrac12\Rightarrow k=\tfrac{\ln2}{12}=0.0578\). (b) \(m=80e^{-0.0578\times20}=80e^{-1.155}=25.2\,\text{g}\). (c) \(20=80e^{-kt}\Rightarrow t=\tfrac{\ln4}{0.0578}=24\,\text{years}\). (d) \(\tfrac{dm}{dt}=-km_0\) at \(t=0=-0.0578(80)=-4.62\,\text{g/year}\).

PastPaper.markingScheme

M1A1 k; M1A1 (b); M1A1 (c); M1A1 (d).
PastPaper.question 6 · Structured
10 PastPaper.marks
(a) An arithmetic series is \(5,9,13,\dots\). Find the sum of the first 25 terms. (b) A geometric series is \(200,150,112.5,\dots\). Find its sum to infinity. (c) Use the arithmetic-series formula to prove that \(1+3+5+\dots+(2n-1)=n^2\). (d) Find the first term of the series in (a) that exceeds 100.
PastPaper.showAnswers

PastPaper.workedSolution

(a) \(a=5,d=4\): \(S_{25}=\tfrac{25}{2}(10+24(4))=\tfrac{25}{2}(106)=1325\). (b) \(r=0.75\): \(\tfrac{200}{1-0.75}=800\). (c) AP with \(a=1,d=2\): \(S_n=\tfrac n2(2+(n-1)2)=n^2\). (d) \(5+(n-1)4>100\Rightarrow n>24.75\Rightarrow n=25\) (term \(=101\)).

PastPaper.markingScheme

M1A1 (a); M1A1 (b); M1A1 (c); M1A1 (d).
PastPaper.question 7 · Multiple choice
1 PastPaper.marks
For \(X\sim B(25,0.2)\), state the mean \(E(X)\). Circle your answer.
  1. A.\(0.2\)
  2. B.\(5\)
  3. C.\(4\)
  4. D.\(20\)
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PastPaper.workedSolution

\(E(X)=np=25\times0.2=5\).

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B1 for 5.
PastPaper.question 8 · Structured
6 PastPaper.marks
(a) Define a simple random sample. (b) A college has 600 students, each with an ID number. Describe how to take a simple random sample of 60. (c) State one advantage of stratified sampling here.
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(a) A simple random sample is one in which every possible sample of the required size is equally likely (every member has an equal chance of selection). (b) Number students 1–600; use random numbers to choose 60 distinct IDs, ignoring repeats and numbers above 600. (c) Stratified sampling represents each subgroup (e.g. year group) in proportion, reducing bias.

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B1 definition; M1 numbering; A1 random selection; B1 advantage; B1 reason; B1 clarity.
PastPaper.question 9 · Structured
10 PastPaper.marks
Eight values are \(10,12,14,15,18,20,24,28\). (a) Find the median. (b) Find \(Q_1\), \(Q_3\) and the IQR. (c) Find the mean. (d) Find the standard deviation to 2 decimal places. (e) Using the \(1.5\times\text{IQR}\) rule, determine whether 28 is an outlier.
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PastPaper.workedSolution

(a) Median \(=\tfrac{15+18}{2}=16.5\). (b) \(Q_1=12,\,Q_3=22\) (mean of 20 and 24), \(\text{IQR}=10\). (c) Mean \(=\tfrac{141}{8}=17.625\). (d) \(\sum x^2=2749\); variance \(=\tfrac{2749}{8}-17.625^2=32.98\); s.d. \(=5.74\). (e) \(Q_3+1.5(10)=37>28\), so 28 is not an outlier.

PastPaper.markingScheme

B1 median; B1 quartiles; B1 IQR; M1A1 mean; M1A1 s.d.; B1 outlier.
PastPaper.question 10 · Structured
10 PastPaper.marks
The masses of items are modelled by \(X\sim N(50,6^2)\) (in grams). (a) Find \(P(X>56)\). (b) Find \(P(44
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PastPaper.workedSolution

(a) \(z=\tfrac{56-50}{6}=1\Rightarrow P(Z>1)=0.1587\). (b) \(z=-1\) and \(z=1.5\Rightarrow\Phi(1.5)-\Phi(-1)=0.9332-0.1587=0.7745\). (c) \(P(X>x)=0.05\Rightarrow z=1.645\Rightarrow x=50+1.645(6)=59.9\,\text{g}\).

PastPaper.markingScheme

M1 standardise; A1 (a); M1A1 (b); M1 z=1.645; A1 (c).
PastPaper.question 11 · Structured
10 PastPaper.marks
(a) For \(X\sim B(12,0.35)\) find (i) \(P(X=4)\) and (ii) \(P(X\le2)\). (b) A coin-like process is claimed to succeed with probability greater than 0.35. In 12 trials there are 9 successes. Test at the 5% level whether the success probability exceeds 0.35.
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PastPaper.workedSolution

(a)(i) \(\binom{12}{4}0.35^4 0.65^8=0.2367\). (ii) \(P(X\le2)=0.1513\). (b) \(H_0:p=0.35\), \(H_1:p>0.35\), \(X\sim B(12,0.35)\). \(P(X\ge9)=1-P(X\le8)=0.0028<0.05\), so reject \(H_0\): evidence the success probability exceeds 0.35.

PastPaper.markingScheme

M1A1 (a)(i); A1 (a)(ii); B1 hypotheses; M1 P(X≥9); A1 0.0028; A1 conclusion.
PastPaper.question 12 · Structured
7 PastPaper.marks
Events \(A\) and \(B\) satisfy \(P(A)=0.6\), \(P(B)=0.3\) and \(P(A\cap B)=0.18\). (a) Find \(P(A\cup B)\). (b) Find \(P(B\mid A)\). (c) Determine, with justification, whether \(A\) and \(B\) are independent.
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PastPaper.workedSolution

(a) \(P(A\cup B)=0.6+0.3-0.18=0.72\). (b) \(P(B\mid A)=\tfrac{0.18}{0.6}=0.3\). (c) \(P(A)P(B)=0.6(0.3)=0.18=P(A\cap B)\), so \(A\) and \(B\) are independent.

PastPaper.markingScheme

M1A1 (a); M1A1 (b); M1 compare; A1 conclusion.
PastPaper.question 13 · Structured
6 PastPaper.marks
The discrete random variable \(X\) has \(P(X=0)=0.1,\,P(X=1)=0.3,\,P(X=2)=0.4,\,P(X=3)=0.2\). (a) Find \(E(X)\). (b) Find \(\text{Var}(X)\). (c) Find \(E(3X-2)\).
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PastPaper.workedSolution

(a) \(E(X)=0(0.1)+1(0.3)+2(0.4)+3(0.2)=1.7\). (b) \(E(X^2)=0+0.3+1.6+1.8=3.7\); \(\text{Var}(X)=3.7-1.7^2=0.81\). (c) \(E(3X-2)=3(1.7)-2=3.1\).

PastPaper.markingScheme

M1A1 E(X); M1 E(X²); A1 Var; A1 (c).

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