Topic – E1.1
Write down a prime number between 30 and 40.
▶️ Answer/Explanation
Ans: 31 or 37
Prime numbers between 30 and 40 are numbers divisible only by 1 and themselves. Checking each number: 31 (prime), 32 (not), 33 (not), 34 (not), 35 (not), 36 (not), 37 (prime), 38 (not), 39 (not).
Topic – E1.7
Calculate \( 4^5 – 5^4 \).
▶️ Answer/Explanation
Ans: 399
Calculate each term: \(4^5 = 1024\) and \(5^4 = 625\). Then subtract: \(1024 – 625 = 399\).
Topic – E1.15
Jason starts a run at 10.05 am and finishes at 1.02 pm.
Work out the time Jason takes to complete the run.
▶️ Answer/Explanation
Ans: 2h 57min
From 10:05 am to 1:02 pm is 2 hours and 57 minutes (10:05 to 1:05 would be 3 hours, subtract 3 minutes).
Topic – E1.4
Calculate \( \frac{1 – 0.7}{0.45 – 0.38} \), giving your answer correct to 4 significant figures.
▶️ Answer/Explanation
Ans: 4.286
Numerator: \(1 – 0.7 = 0.3\). Denominator: \(0.45 – 0.38 = 0.07\). Divide: \(0.3 ÷ 0.07 ≈ 4.2857\). Round to 4 significant figures: 4.286.
Topic – E1.16
Kirsty changes $380.80 into pounds (£) when £1 = $1.19.
Calculate the amount Kirsty receives.
▶️ Answer/Explanation
Ans: 320
Divide dollars by exchange rate: \(380.80 ÷ 1.19 = 320\). So Kirsty receives £320.
Topic – E1.1
Write 180 as a product of its prime factors.
▶️ Answer/Explanation
Answer: $2 \times 2 \times 3 \times 3 \times 5$ or $2^2 \times 3^2 \times 5$
1. Start dividing by the smallest prime number, 2: 180 ÷ 2 = 90
2. Continue dividing by 2: 90 ÷ 2 = 45
3. Now divide by 3: 45 ÷ 3 = 15
4. Again divide by 3: 15 ÷ 3 = 5
5. Finally divide by 5: 5 ÷ 5 = 1
The prime factors are all the divisors used: 2, 2, 3, 3, 5
Topic – E1.4
Without using a calculator, work out $\frac{3}{7} – \frac{2}{21}$.
You must show all your working and give your answer as a fraction in its simplest form.
▶️ Answer/Explanation
Answer: $\frac{1}{3}$
1. Find common denominator: 7 and 21 → LCD is 21
2. Convert $\frac{3}{7}$ to $\frac{9}{21}$ (multiply numerator and denominator by 3)
3. Now subtract: $\frac{9}{21} – \frac{2}{21} = \frac{7}{21}$
4. Simplify $\frac{7}{21}$ by dividing numerator and denominator by 7 → $\frac{1}{3}$
Topic – E2.5
$s = \frac{1}{2} at^2$
(a) Work out the value of $s$ when $a = 0.9$ and $t = 4$.
(b) Rearrange the formula to find $t$ in terms of $s$ and $a$.
▶️ Answer/Explanation
8(a) Answer: 7.2
Substitute values: $s = \frac{1}{2} \times 0.9 \times 4^2 = 0.45 \times 16 = 7.2$
8(b) Answer: $t = \pm \sqrt{\frac{2s}{a}}$
1. Start with $s = \frac{1}{2} at^2$
2. Multiply both sides by 2: $2s = at^2$
3. Divide both sides by $a$: $\frac{2s}{a} = t^2$
4. Take square root of both sides: $t = \pm \sqrt{\frac{2s}{a}}$
(Note: The ± is included because time can be considered positive in physical contexts, but mathematically both roots exist)
Topic – E2.2
Factorise completely: $14xy – 7y^2$
▶️ Answer/Explanation
Answer: $7y(2x – y)$
1. Identify common factors in both terms: 7 and y
2. Factor out 7y from both terms: $7y(2x) – 7y(y)$
3. This becomes $7y(2x – y)$
Check by expanding back: $7y \times 2x = 14xy$ and $7y \times (-y) = -7y^2$
Topic – E2.7
22, 17, 12, 7, 2, …
(a) Find the next term of the sequence.
(b) Find the nth term of the sequence.
▶️ Answer/Explanation
10(a) Answer: -3
The sequence decreases by 5 each time: 22, 17 (-5), 12 (-5), 7 (-5), 2 (-5), so next term is 2 – 5 = -3
10(b) Answer: $27 – 5n$
1. The common difference is -5
2. The 0th term would be 22 + 5 = 27
3. So nth term formula is: first term + (n-1)×difference
Or: 0th term + n×difference → 27 + n×(-5) = 27 – 5n
Topic – E4.4
Triangle ABC is mathematically similar to triangle PQR.
(a) Calculate QR.
(b) The two triangles are the cross-sections of two mathematically similar prisms. The volume of the larger prism is 320 cm³.
Calculate the volume of the smaller prism.
▶️ Answer/Explanation
Ans:
(a) 4.5 cm (Using similarity ratio: 8/6 = 6/QR → QR = 6×6/8)
(b) 135 cm³ (Volume ratio is cube of linear ratio: (6/8)³ × 320)
Topic – E4.6
The interior angles of a pentagon are in the ratio 4 : 5 : 5 : 7 : 9.
Find the size of the largest angle.
▶️ Answer/Explanation
Ans: 162°
Sum of interior angles = (5-2)×180° = 540°
Total ratio parts = 4+5+5+7+9 = 30
Largest angle = (9/30)×540° = 162°
Topic – E1.8
Work out $2 \times 10^{100} – 2 \times 10^{98}$, giving your answer in standard form.
▶️ Answer/Explanation
Ans: $1.98 \times 10^{100}$
Factor out $2 \times 10^{98}$ to get $2 \times 10^{98}(100 – 1)$
This equals $2 \times 10^{98} \times 99 = 198 \times 10^{98}$
Convert to standard form: $1.98 \times 10^{100}$
Topic – E1.12
A train passes through a station at a speed of 108 km/h.
The length of the station is 120 m.
The train takes 7 seconds to completely pass through the station.
Work out the length of the train.
▶️ Answer/Explanation
Ans: 90 m
Convert speed to m/s: 108 km/h = 108000 m/3600 s = 30 m/s
Total distance covered = speed × time = 30 × 7 = 210 m
Train length = total distance – station length = 210 – 120 = 90 m
Topic – E2.4
Find the value of x.
$4^{x} = \frac{1}{64}$
▶️ Answer/Explanation
Ans: -3
Express both sides with base 4: $4^x = 4^{-3}$ (since $64 = 4^3$)
Therefore, $x = -3$
Topic – E7.1
Describe fully the single transformation that maps triangle T onto triangle P.
▶️ Answer/Explanation
Ans: Enlargement with scale factor ½, center (4,4)
1. Observe triangle P is half the size of triangle T
2. Check lines from center point (4,4) to corresponding vertices
3. Confirm all distances are halved from center (4,4)
Topic – E5.4
Find the radius of a hemisphere of volume 80 cm³.
[The volume, V, of a sphere with radius r is $V = \frac{4}{3}πr^3$]
▶️ Answer/Explanation
Ans: 3.37 cm
1. Hemisphere volume = ½ sphere volume: $\frac{2}{3}πr^3 = 80$
2. Rearrange: $r^3 = \frac{80×3}{2π} = \frac{120}{π}$
3. Calculate: $r = \sqrt[3]{\frac{120}{π}} ≈ 3.37$ cm
Topic – E4.7
A, B, C and D are points on a circle.
TU is a tangent to the circle at D.
DA is parallel to CB.
Find the value of x and the value of y.
▶️ Answer/Explanation
Ans: x = 38, y = 22
1. x = angle between tangent and chord = angle in alternate segment (38°)
2. Since DA ∥ CB, angle CBA = 180° – 38° = 142°
3. In triangle ABC: y = 180° – 38° – 120° = 22°
Topic – E4.4
In the diagram, AB is parallel to PQ.
AQ and PB intersect at X with .
Complete the following statements.
In triangles ABX and QPX,
AX XQ = is given information.
Angle BAX Angle = ….. because …………….
Angle AXB Angle = ….. because ……………..
Triangle ABX is congruent to triangle QPX because of the congruency criterion ………….
PX = ……. because the triangles are congruent.
▶️ Answer/Explanation
Ans:
Angle BAX = Angle PQX (alternate angles)
Angle AXB = Angle PXQ (vertically opposite angles)
Triangle ABX ≡ triangle QPX (ASA congruency)
PX = XB (corresponding sides of congruent triangles)
Topic – E2.9
The diagram shows the speed-time graph for 24 seconds of a car journey.
(a) Calculate the deceleration of the car in the final 8 seconds.
(b) Calculate the total distance travelled during the 24 seconds.
▶️ Answer/Explanation
Ans:
(a) 1.5 m/s² (Deceleration = (12-0)/8 = 1.5 m/s²)
(b) 240 m (Area under graph: (16×12) + ½(8×12) = 192 + 48 = 240 m)
Topic – E2.2
Factorise completely: $1 – q – a + aq$
▶️ Answer/Explanation
Ans: $(1-q)(1-a)$
1. Group terms: $(1 – q) + (-a + aq)$
2. Factorise: $(1 – q) – a(1 – q)$
3. Common factor: $(1 – q)(1 – a)$
Topic – E2.4
Simplify fully $(216y^{216})^{\frac{2}{3}}$.
▶️ Answer/Explanation
Ans: $36y^{144}$
First simplify $216^{\frac{2}{3}}$ = $(6^3)^{\frac{2}{3}} = 6^2 = 36$.
Then $(y^{216})^{\frac{2}{3}} = y^{216 \times \frac{2}{3}} = y^{144}$.
Combine both parts to get $36y^{144}$.
Topic – E2.2
(a) $x^2 + 8x + 10 = (x + p)^2 + q$
Find the value of $p$ and the value of $q$.
(b) Solve $x^2 + 8x + 10 = 30$.
▶️ Answer/Explanation
Ans (a): p = 4, q = -6
Complete the square: $(x^2 + 8x) + 10 = (x + 4)^2 – 16 + 10 = (x + 4)^2 – 6$.
Ans (b): x = -10 or x = 2
Using part (a): $(x + 4)^2 – 6 = 30$ → $(x + 4)^2 = 36$ → $x + 4 = ±6$.
So $x = -4 ±6$ giving solutions -10 and 2.
Topic – E6.1
A cuboid measures 24 cm by 12 cm by 8 cm.
Calculate the length of a diagonal of the cuboid.
▶️ Answer/Explanation
Ans: 28 cm
Use 3D Pythagoras: $\sqrt{24^2 + 12^2 + 8^2}$.
Calculate: $\sqrt{576 + 144 + 64} = \sqrt{784} = 28$ cm.
Topic – E1.11
$w$ is proportional to the square root of $y$.
$y$ is inversely proportional to $x$.
When $x = 4$, $y = 16$ and $w = 8$.
Find $w$ in terms of $x$.
▶️ Answer/Explanation
Ans: $\frac{16}{\sqrt{x}}$
First find $y = \frac{k}{x}$ → $16 = \frac{k}{4}$ → $k = 64$, so $y = \frac{64}{x}$.
Then $w = m\sqrt{y}$ → $8 = m\sqrt{16}$ → $m = 2$.
Substitute: $w = 2\sqrt{\frac{64}{x}} = \frac{16}{\sqrt{x}}$.
Topic – E7.1
The diagram shows a triangle $OAB$ and a parallelogram $OALK$.
The position vector of $A$ is a and the position vector of $B$ is b.
$K$ is a point on $AB$ so that $AK : KB = 1 : 2$.
Find the position vector of $L$, in terms of a and b.
Give your answer in its simplest form.
▶️ Answer/Explanation
Ans: $\frac{5}{3}a + \frac{1}{3}b$
Find $\overrightarrow{AK} = \frac{1}{3}\overrightarrow{AB} = \frac{1}{3}(b – a)$.
Since $OALK$ is parallelogram, $\overrightarrow{AL} = \overrightarrow{OK} = \overrightarrow{OA} + \overrightarrow{AK} = a + \frac{1}{3}(b – a)$.
Thus $\overrightarrow{OL} = \overrightarrow{OA} + \overrightarrow{AL} = a + \frac{1}{3}(b – a) + a = \frac{5}{3}a + \frac{1}{3}b$.
Topic – E2.10
The line $y = x + 1$ intersects the graph of $y = x^2 – 3x – 11$ at the points $A$ and $B$.
Find the coordinates of $A$ and the coordinates of $B$.
▶️ Answer/Explanation
Ans: A(-2, -1) and B(6, 7)
Set equations equal: $x^2 – 3x – 11 = x + 1$ → $x^2 – 4x – 12 = 0$.
Factorize: $(x + 2)(x – 6) = 0$ → $x = -2$ or $6$.
Find y-coordinates: when $x = -2$, $y = -1$; when $x = 6$, $y = 7$.