Topic – E1.1
Write down a common multiple of 18 and 24.
▶️ Answer/Explanation
Ans: Any multiple of 72
Find the LCM of 18 and 24:
Prime factors of 18: $2 × 3^2$
Prime factors of 24: $2^3 × 3$
LCM = $2^3 × 3^2 = 72$
Any multiple of 72 (e.g., 72, 144, 216) is correct.
Topic – E1.15
A train journey starts at 23.40 and finishes at 06.50.
Work out the time taken for this journey.
▶️ Answer/Explanation
Ans: 7 h 10 min
From 23:40 to midnight: 20 minutes
From midnight to 06:50: 6 hours 50 minutes
Total time = 20 min + 6 h 50 min = 7 h 10 min
Topic – E1.4
Write 32 cm as a fraction of 2 m.
Give your answer in its simplest form.
▶️ Answer/Explanation
Ans: $\frac{4}{25}$
Convert 2 m to cm: 2 m = 200 cm
Fraction = $\frac{32}{200}$
Simplify by dividing numerator and denominator by 8: $\frac{4}{25}$
Topic – E1.11
Divide $200 in the ratio 7:3.
▶️ Answer/Explanation
Ans: $140, $60
Total parts = 7 + 3 = 10
Value per part = $200 ÷ 10 = $20
First part = 7 × $20 = $140
Second part = 3 × $20 = $60
Topic – E4.6
The diagram shows two straight lines intersecting two parallel lines.
Find the value of $x$.
▶️ Answer/Explanation
Ans: $x = 54$
Using the fact that angles in a triangle sum to $180^\circ$:
First find the angle adjacent to $71^\circ$: $180^\circ – 71^\circ – 55^\circ = 54^\circ$
This angle is equal to $x$ due to alternate angles being equal for parallel lines.
Topic – E1.13
The price of a computer is $520.
This price is reduced by 15% in a sale.
Work out the sale price.
▶️ Answer/Explanation
Ans: $442
Method 1: Calculate 15% of $520 = $78, then subtract from original price: $520 – $78 = $442
Method 2: Calculate 85% of $520 directly: 0.85 × 520 = $442
Topic – E1.2
The Venn diagram shows the elements of the sets E, P and Q.
Complete the statements.
(a) P = {……}
(b) n(P ∪ Q) = ……
▶️ Answer/Explanation
Ans:
(a) P = {a, b, c, d}
(b) n(P ∪ Q) = 6
For (a), list all elements in circle P.
For (b), count all unique elements in P and Q combined.
Topic – E2.7
(a) 3, 9, 27, 81, …
Write down the next term in this sequence.
(b) 13, 17, 21, 25, …
Find the nth term of this sequence.
▶️ Answer/Explanation
Ans:
(a) 243 (each term is multiplied by 3)
(b) 4n + 9
For (a), recognize the geometric sequence pattern (×3).
For (b), find common difference (4) and adjust for first term: 4×1 + 9 = 13.
Topic – E1.4
Without using a calculator, work out $\frac{1}{3} + \frac{5}{6}$.
You must show all your working and give your answer as a mixed number in its simplest form.
▶️ Answer/Explanation
Ans: $1\frac{1}{6}$
Convert $\frac{1}{3}$ to $\frac{2}{6}$ to get common denominator.
$\frac{2}{6} + \frac{5}{6} = \frac{7}{6} = 1\frac{1}{6}$
Topic – E2.4
Simplify $18x^{18} ÷ 9x^9$.
▶️ Answer/Explanation
Ans: $2x^9$
Divide coefficients: 18 ÷ 9 = 2
Subtract exponents: $x^{18} ÷ x^9 = x^{18-9} = x^9$
Combine results: $2x^9$
Topic – E2.5
Solve the simultaneous equations.
$x – 3y = 7$
$2x – 3y = 11$
▶️ Answer/Explanation
Ans: x = 4, y = -1
Subtract first equation from second: (2x – 3y) – (x – 3y) = 11 – 7
This gives x = 4
Substitute x = 4 into first equation: 4 – 3y = 7 → -3y = 3 → y = -1
Topic – E4.4
Triangle PQR is similar to triangle ABC with $\frac{PR}{AC} = \frac{2}{3}$.
AB = 9 cm and the area of triangle ABC is 18 cm².
(a) Find the length of PQ.
(b) Find the area of triangle PQR.
▶️ Answer/Explanation
Ans: (a) 6 cm (b) 8 cm²
(a) Since PR/AC = 2/3, all corresponding sides have ratio 2:3. PQ/AB = 2/3 → PQ = (2/3)×9 = 6 cm
(b) Area ratio is square of side ratio: (2/3)² = 4/9. Area PQR = (4/9)×18 = 8 cm²
Topic – E2.9
The diagram shows the speed-time graph of the first 15 seconds of a car journey.
(a) Find the acceleration of the car during the first 5 seconds.
(b) Find the distance travelled during the 15 seconds.
▶️ Answer/Explanation
Ans: (a) 2.8 m/s² (b) 175 m
(a) Acceleration = gradient = 14 m/s ÷ 5 s = 2.8 m/s²
(b) Distance = area under graph = triangle (½×5×14) + rectangle (10×14) = 35 + 140 = 175 m
Topic – E7.1
Describe fully the single transformation that maps triangle A onto triangle B.
▶️ Answer/Explanation
Ans: Rotation, 90° clockwise about (5,3)
From the diagram, triangle B is a 90° clockwise rotation of triangle A. The center of rotation is where the perpendicular bisectors of corresponding points meet, which is at (5,3).
Topic – E5.3
The perimeter of a sector of a circle with radius 8 cm is 26 cm.
Calculate the angle of this sector.
▶️ Answer/Explanation
Ans: 71.6°
Perimeter = 2 radii + arc length: 26 = 8 + 8 + (θ/360)×2π×8
Arc length = 10 cm → θ = (10×360)/(16π) ≈ 71.6°
Topic – E4.7
The diagram shows a circle and eight chords.
Calculate the values of \( u \), \( v \), \( w \) and \( x \).
▶️ Answer/Explanation
Ans: \( u = 20 \), \( v = 52 \), \( w = 108 \), \( x = 36 \)
1. \( u = 20° \) (given angle)
2. \( v = 180 – 72 – 56 = 52° \) (angles in triangle)
3. \( w = 180 – 72 = 108° \) (angles on straight line)
4. \( x = 180 – 108 – 36 = 36° \) (angles in triangle)
Topic – E2.4
Simplify \( \left(3125x^{3125}\right)^{\frac{1}{5}} \).
▶️ Answer/Explanation
Ans: \( 5x^{625} \)
1. Recognize 3125 is \( 5^5 \)
2. Apply exponent rules: \( (5^5)^{\frac{1}{5}} = 5 \)
3. For \( x \) term: \( 3125 \times \frac{1}{5} = 625 \)
4. Combine results: \( 5x^{625} \)
Topic – E6.2
Calculate the length \( BC \).
▶️ Answer/Explanation
Ans: 12.7 cm (12.68 to 12.69)
1. Find angle C: \( 180 – 115 – 35 = 30° \)
2. Apply sine rule: \( \frac{BC}{\sin 115} = \frac{7}{\sin 30} \)
3. Calculate: \( BC = \frac{7 \times \sin 115}{\sin 30} \)
4. Evaluate: \( \sin 115 ≈ 0.9063 \), \( \sin 30 = 0.5 \)
5. Final calculation: \( BC ≈ 12.688 \) cm
Topic – E2.2
Expand and simplify \( (2x + 3)(x – 2)^2 \).
▶️ Answer/Explanation
Ans: \( 2x^3 – 5x^2 – 4x + 12 \)
1. First expand \( (x – 2)^2 = x^2 – 4x + 4 \)
2. Multiply by \( (2x + 3) \): \( 2x(x^2 – 4x + 4) + 3(x^2 – 4x + 4) \)
3. Expand: \( 2x^3 – 8x^2 + 8x + 3x^2 – 12x + 12 \)
4. Combine like terms: \( 2x^3 – 5x^2 – 4x + 12 \)
Topic – E2.2
Factorise completely:
(a) \( 1 + x – y – xy \)
(b) \( 2x^3 – 18xy^2 \)
▶️ Answer/Explanation
Ans:
(a) \( (1 + x)(1 – y) \)
1. Group terms: \( (1 + x) – y(1 + x) \)
2. Factor out common \( (1 + x) \) term
(b) \( 2x(x + 3y)(x – 3y) \)
1. Factor out 2x: \( 2x(x^2 – 9y^2) \)
2. Recognize difference of squares: \( x^2 – 9y^2 = (x + 3y)(x – 3y) \)
3. Combine factors
Topic – E2.11
The graph of a cubic function has two turning points.
When $x < 0$ and when $x > 4$ the gradient of the graph is positive.
When $0 < x < 4$ the gradient of the graph is negative.
The graph passes through the origin.
Sketch the graph.
▶️ Answer/Explanation
Sketch should show:
1. A cubic curve with maximum at origin (0,0)
2. A minimum point somewhere in the range 0 < x < 4
3. Positive gradient for x < 0 and x > 4
4. Negative gradient between 0 < x < 4
Topic – E2.10
(a) On the diagram, sketch the graph of $y = \cos x$ for $0^\circ \leq x \leq 360^\circ$.
(b) Solve the equation $\cos x = -\frac{1}{2}$ for $0^\circ \leq x \leq 360^\circ$.
▶️ Answer/Explanation
(a)
The cosine graph should start at (0°,1), decrease to (180°,-1), and return to (360°,1), forming a smooth wave.
(b) $x = 120^\circ$ or $x = 240^\circ$
These are the angles in the range where cosine equals -1/2. 120° is in the second quadrant and 240° is in the third quadrant.
Topic – E1.11
$y$ is inversely proportional to $\sqrt{x}$ and $x$ is directly proportional to $w^2$.
When $w = 12$, $y = 12$.
Find $y$ in terms of $w$.
▶️ Answer/Explanation
$y = \frac{144}{w}$
1. First relationship: $y = \frac{k}{\sqrt{x}}$
2. Second relationship: $x = mw^2$
3. Combine: $y = \frac{k}{\sqrt{mw^2}} = \frac{k}{\sqrt{m}w}$
4. Substitute w=12, y=12 to find k/√m = 144
Topic – E1.10
Violet and Wilfred recorded their times to run 200 m, correct to the nearest second.
Violet took 36 seconds and Wilfred took 39 seconds.
Work out the upper bound of the difference between their times.
▶️ Answer/Explanation
4 seconds
1. Violet’s time range: 35.5 ≤ t < 36.5
2. Wilfred’s time range: 38.5 ≤ t < 39.5
3. Maximum difference occurs when Violet’s time is minimum (35.5) and Wilfred’s is maximum (39.5)
4. Difference: 39.5 – 35.5 = 4 seconds
Topic – E8.1
A bag contains 5 red balls, 4 blue balls and 3 green balls.
(a) (i) Megan picks a ball at random. Write down the probability that the ball is red or blue.
(ii) Megan replaces the ball.
She picks a ball at random, notes the colour and replaces the ball.
She repeats this 60 times.
Calculate the number of times the ball is expected to be red or blue.
(b) Mick picks 2 of the 12 balls at random, without replacement. Calculate the probability that the balls are different colours.
(c) Marie picks balls at random, without replacement, from the 12 balls.
When she picks a green ball she stops.
The probability that she picks a green ball on pick $n$ is $\frac{21}{220}$.
Find the value of $n$.
▶️ Answer/Explanation
(a)(i) $\frac{3}{4}$ (9 balls out of 12 are red or blue)
(a)(ii) 45 (60 × 3/4)
(b) $\frac{47}{66}$
1. Total ways to pick 2 balls: 12C2 = 66
2. Calculate 1 – P(same color) = 1 – (5C2 + 4C2 + 3C2)/66
(c) n = 5
This is found by calculating when P(green on nth pick without replacement) = 21/220