Topic – E2.7
These are the first eight terms of a sequence.
c -3 -9 -15 -21 -27 -33 k
Find the value of c and the value of k.
▶️ Answer/Explanation
Ans: c = 3, k = -39
The sequence decreases by 6 each time (arithmetic sequence).
Working backwards: -3 + 6 = 3 → c = 3
Working forwards: -33 – 6 = -39 → k = -39
Topic – E4.6
The diagram shows an isosceles triangle.
Find the value of x.
▶️ Answer/Explanation
Ans: x = 94
In an isosceles triangle, base angles are equal (both 43°).
Sum of angles in triangle = 180°
x + 43° + 43° = 180°
x = 180° – 86° = 94°
Topic – E1.1
Complete each statement with a number from the list:
…… is a natural number.
…… is an irrational number.
…… is the reciprocal of 4.
▶️ Answer/Explanation
Ans: 24, √3, 0.25
24 is a natural number (positive integer).
√3 is irrational (cannot be expressed as a fraction).
0.25 is the reciprocal of 4 (1/4 = 0.25).
Topic – E9.4
The scatter diagram shows the number of rooms and the number of people in each of eight buildings.
(a) One building has 67 rooms. Write down the number of people in this building.
(b) In another building there are 42 people and 33 rooms. Plot this point.
(c) (i) Draw a line of best fit.
(ii) Estimate the number of rooms for 45 people.
(d) What type of correlation is shown?
▶️ Answer/Explanation
Ans:
(a) 76 people
(b) Point plotted at (42,33)
(c)(i) Straight line through middle of data points
(c)(ii) 27-33 rooms (depending on line)
(d) Positive correlation (as rooms increase, people increase)
Topic – E5.1
Convert 7.51 m² into cm².
▶️ Answer/Explanation
Ans: 75100 cm²
1 m = 100 cm
1 m² = 100 × 100 = 10,000 cm²
7.51 m² = 7.51 × 10,000 = 75,100 cm²
Topic – E5.2
The diagram shows a trapezium.
The area of the trapezium is \(42cm^{2}\)
Calculate the value of x.
▶️ Answer/Explanation
Ans: 4.5
Area of trapezium = ½ × (sum of parallel sides) × height
42 = ½ × (9.5 + x) × 6
42 = 3 × (9.5 + x)
14 = 9.5 + x
x = 4.5 cm
Topic – E1.4
Without using a calculator, work out $\frac{2}{7} ÷ \frac{6}{11}$.
Give your answer as a fraction in its simplest form.
▶️ Answer/Explanation
Ans: $\frac{11}{21}$
Dividing by a fraction is same as multiplying by its reciprocal
$\frac{2}{7} ÷ \frac{6}{11} = \frac{2}{7} × \frac{11}{6}$
Multiply numerators and denominators: $\frac{22}{42}$
Simplify by dividing numerator and denominator by 2: $\frac{11}{21}$
Topic – E4.6
The diagram shows a parallelogram.
Work out the size of the smallest interior angle of the parallelogram.
▶️ Answer/Explanation
Ans: 70°
Adjacent angles in parallelogram add to 180°
(132-2x) + (15+5x) = 180
147 + 3x = 180 → 3x = 33 → x = 11
First angle: 132 – 2(11) = 110°
Second angle: 15 + 5(11) = 70°
Topic – E5.3
Points A, B, C and D lie on a circle.
ABCD is a square with area 72 cm².
Calculate the area of the circle. Give your answer as a multiple of π.
▶️ Answer/Explanation
Ans: 36π cm²
Square area = side² = 72 → side = √72 cm
Diagonal of square = diameter of circle = √72 × √2 = √144 = 12 cm
Radius = 6 cm
Area of circle = πr² = π × 6² = 36π cm²
Topic – E1.14
Calculate $\sqrt[3]{1 + 10.9 \times 0.4^{2}}$.
▶️ Answer/Explanation
Ans: 1.4
First calculate $0.4^2 = 0.16$.
Then multiply: $10.9 \times 0.16 = 1.744$.
Add 1: $1 + 1.744 = 2.744$.
Finally take cube root: $\sqrt[3]{2.744} = 1.4$.
Topic – E2.2
Factorise fully.
(a) 24x² – 9xy
(b) 63x² – 28y²
▶️ Answer/Explanation
(a) Ans: 3x(8x – 3y)
Take out common factor 3x: 3x(8x) – 3x(3y) = 3x(8x – 3y)
(b) Ans: 7(3x + 2y)(3x – 2y)
First take out 7: 7(9x² – 4y²). Then recognize difference of squares: 7(3x + 2y)(3x – 2y)
Topic – E2.8
y is directly proportional to the square root of (x + 1).
y = 10.5 when x = 8.
Find y when x = 1.56.
▶️ Answer/Explanation
Ans: 5.6
First write equation: y = k√(x+1). Substitute y=10.5, x=8 to find k=3.5.
Then use k to find y when x=1.56: y = 3.5√(1.56+1) = 3.5×1.6 = 5.6
Topic – E2.6
The region R satisfies these inequalities:
-3 < y ≤ 2 y ≤ x – 1
By drawing suitable straight lines and shading unwanted regions, find and label the region R.
▶️ Answer/Explanation
Ans:
1. Draw dashed line y=-3 (not included) and shade above it
2. Draw solid line y=2 (included) and shade below it
3. Draw solid line y=x-1 (included) and shade below it
The region R is where all three conditions overlap
Topic – E2.9
The diagram shows the speed-time graph for 17 seconds of a car journey.
(a) Find the acceleration of the car during the first 10 seconds.
(b) Calculate the total distance travelled by the car during the 17 seconds.
▶️ Answer/Explanation
(a) Ans: 2 m/s²
Acceleration = gradient = (20-0)/10 = 2 m/s²
(b) Ans: 240 m
Distance = area under graph = (½×10×20) + (7×20) = 100 + 140 = 240 m
Topic – E1.17
At the start of an experiment there are 40,000 bacteria.
The number of bacteria increases at a rate of 15% per hour.
Calculate the number of bacteria after 3 hours.
▶️ Answer/Explanation
Ans: 60,835
Use compound growth formula: 40,000 × (1.15)³
First hour: 40,000 × 1.15 = 46,000
Second hour: 46,000 × 1.15 = 52,900
Third hour: 52,900 × 1.15 = 60,835
Topic – E8.4
75 people are asked if they have a car, C, and if they have a job, J.
The Venn diagram shows the results.
A person is chosen at random from those who have a car.
Find the probability that this person also has a job.
▶️ Answer/Explanation
Ans: 17/20
From the Venn diagram:
People with cars (C) = 9 (C∩J) + 51 (C only) = 60
People with jobs among car owners = 9 (C∩J)
The Venn diagram shows:
• People with both car and job (C∩J) = 51
• People with car only = 9
• Therefore probability = 51/(51+9) = 51/60 = 17/20
Topic – E4.8
A, B and C are points on the circumference of a circle with center O.
DA and DC are tangents to the circle.
Angle ABC = 64°.
Work out the value of x.
▶️ Answer/Explanation
Ans: 52
Angle at center AOC = 2 × angle ABC = 128°.
Tangents meet radius at 90°, so angles OAD and OCD are 90°.
Quadrilateral AOCD has angles summing to 360°: 90 + 90 + 128 + x = 360.
Therefore x = 360 – 308 = 52°.
Topic – E1.2
(a) ξ = {8×10⁻¹, 0.8̇, 8%, 0.08}
A = {a: 0.08 ≤ a ≤ 1}
B = {b: b > 0.8}
Complete the Venn diagram.
(b) Shade the region (A∪C)∩B’ in the Venn diagram.
▶️ Answer/Explanation
18(a) Answer:
First convert all numbers to decimal form:
8×10⁻¹ = 0.8
0.8̇ (recurring) = 0.888…
8% = 0.08
0.08 remains 0.08
Set A (0.08 ≤ a ≤ 1) contains: 0.8, 0.8̇, 0.08
Set B (b > 0.8) contains: 0.8̇ (only)
Therefore:
• Only in A: 0.8, 0.08
• A∩B: 0.8̇
• Outside both: none (all elements are in A)
18(b) Answer:
To shade (A∪C)∩B’:
1. A∪C means everything in A or C (but C isn’t defined here)
2. B’ means everything not in B
3. The intersection would be all elements that are in (A or C) AND not in B
Assuming C is empty, this would be all elements of A not in B: 0.8 and 0.08
Topic – E5.4
A solid is made from a cylinder and a hemisphere, both of radius 4.3 cm.
The cylinder has length 11.9 cm.
a) Calculate the volume of the solid.
[The volume, V, of a sphere with radius r is \(V = \frac{4}{3} \Pi r^{3}\)]
b) Calculate the total surface area of the solid.
[The surface area, A, of a sphere with radius r is \(A = 4 \Pi r^{2}\)]
▶️ Answer/Explanation
Ans: a) 858 cm³ b) 496 cm²
a) Hemisphere volume = ⅔πr³ = ⅔π(4.3)³ ≈ 166.5 cm³.
Cylinder volume = πr²h = π(4.3)²(11.9) ≈ 691.2 cm³.
Total volume ≈ 166.5 + 691.2 = 857.7 cm³.
b) Hemisphere area = 2πr² = 2π(4.3)² ≈ 116.2 cm².
Cylinder curved area = 2πrh = 2π(4.3)(11.9) ≈ 321.7 cm².
Total area ≈ 116.2 + 321.7 + π(4.3)² ≈ 496 cm².
Topic – E2.7
Find an expression for the nth term of this sequence.
\(\frac{1}{7}\), 1, 7, 49, 343, 2401, …
▶️ Answer/Explanation
Ans: 7ⁿ⁻²
Observe the pattern: 7⁻¹, 7⁰, 7¹, 7², 7³, 7⁴,…
The first term (n=1) is 7⁻¹ = 1/7.
Second term (n=2) is 7⁰ = 1.
Third term (n=3) is 7¹ = 7.
Therefore, nth term = 7ⁿ⁻².
Topic – E2.2
Expand and simplify.
$(x+3)(x+5)(2x+1)$
▶️ Answer/Explanation
Ans: $2x^3 + 17x^2 + 38x + 15$
First expand $(x+3)(x+5)$ to get $x^2 + 8x + 15$.
Then multiply by $(2x+1)$: $2x^3 + x^2 + 16x^2 + 8x + 30x + 15$.
Combine like terms: $2x^3 + 17x^2 + 38x + 15$.
Topic – E3.5
$A$ is the point (17, 9) and $B$ is the point (23, 39).
Find the equation of the perpendicular bisector of line $AB$. Give your answer in the form $y = mx + c$.
▶️ Answer/Explanation
Ans: $y = -\frac{1}{5}x + 28$
1. Find midpoint: $\left(\frac{17+23}{2}, \frac{9+39}{2}\right) = (20, 24)$
2. Gradient of AB: $\frac{39-9}{23-17} = 5$
3. Perpendicular gradient: $-\frac{1}{5}$ (negative reciprocal)
4. Equation using point-slope form: $y – 24 = -\frac{1}{5}(x – 20)$
5. Simplify: $y = -\frac{1}{5}x + 4 + 24$ → $y = -\frac{1}{5}x + 28$
Topic – E4.4
The small box is mathematically similar to the large box.
The volume of the large box is 72.8% greater than the volume of the small box.
The small box has length 3.5 cm and the large box has length $x$ cm.
Calculate the value of $x$.
▶️ Answer/Explanation
Ans: 4.2
Volume scale factor = 1 + 0.728 = 1.728.
Length scale factor = $\sqrt[3]{1.728} = 1.2$.
Large box length = 3.5 cm × 1.2 = 4.2 cm.