Topic – C9.4
Students at an activity centre choose one of four activities.
The bar chart shows some of their choices.
(a) 5 students choose hiking.
Complete the bar chart.
(b) Write down the most popular activity.
▶️ Answer/Explanation
Ans:
(a) Draw a bar for hiking reaching up to 5 on the frequency axis.
(b) Climbing (as it has the tallest bar in the completed chart).
Topic – C4.2
Draw a line that is perpendicular to line L.
▶️ Answer/Explanation
Ans:
Draw a line that intersects line L at 90 degrees. Use a protractor or set square to ensure the angle is exactly 90 degrees.
Topic – C4.1
(a) The diagram shows a circle.
On the diagram, draw a chord.
(b) Another circle has a diameter of 28 cm.
Find the radius of this circle.
▶️ Answer/Explanation
Ans:
(a) Draw a straight line connecting any two points on the circumference of the circle.
(b) Radius = Diameter ÷ 2 = 28 ÷ 2 = 14 cm.
Topic – C4.3
The scale drawing shows the positions of town A and town B.
The scale is 1 cm represents 15 km.
(a) Find the actual distance between town A and town B.
(b) Measure the bearing of town B from town A.
▶️ Answer/Explanation
Ans:
(a) Measure the distance in cm (7.4 cm) and multiply by 15: 7.4 × 15 = 111 km.
(b) Using a protractor, measure the angle clockwise from north to the line AB: approximately 71°.
Topic – C5.1
Change 0.56 kilometres into metres.
▶️ Answer/Explanation
Ans: 560 m
1 km = 1000 m, so 0.56 km = 0.56 × 1000 = 560 m.
Topic – C1.5
Write these numbers in order, starting with the smallest:
$\frac{6}{17}$ 34% $\frac{9}{25}$ 0.345
▶️ Answer/Explanation
Ans: 34% < 0.345 < $\frac{6}{17}$ < $\frac{9}{25}$
Convert all to decimals: 34% = 0.34, $\frac{6}{17}$ ≈ 0.353, $\frac{9}{25}$ = 0.36
Then order: 0.34 < 0.345 < 0.353 < 0.36
Topic – C4.6
The diagram shows two parallel lines and a straight line crossing them.
Find the value of x and the value of y.
▶️ Answer/Explanation
Ans: x = 112, y = 68
y = 68° (corresponding angles)
x = 180° – 68° = 112° (angles on straight line)
Topic – C9.3
Here is some information about six numbers:
• The lowest number is 37
• The range is 24
• The mode is 43
• The median is 46
• One number is a multiple of 11
Find the other five numbers.
▶️ Answer/Explanation
Ans: 37, 43, 43, 49, 55, 61 (in any order except 37 must be first)
Range 24 → highest = 37 + 24 = 61
Mode 43 → appears at least twice
Median 46 → average of 3rd and 4th numbers is 46
Multiple of 11 → likely 55
Topic – C1.7
Calculate $4^5 – 5^4$.
▶️ Answer/Explanation
Ans: 399
$4^5 = 4 × 4 × 4 × 4 × 4 = 1024$
$5^4 = 5 × 5 × 5 × 5 = 625$
$1024 – 625 = 399$
Topic – C1.15
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: 2 hours 57 minutes
From 10:05 am to 1:02 pm is 2 hours and 57 minutes
10:05 am → 1:05 pm = 3 hours
Subtract 3 minutes to get to 1:02 pm
Topic – C1.4
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
Division: 0.3 ÷ 0.07 ≈ 4.285714…
Rounded to 4 significant figures: 4.286
Topic – C1.16
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
Calculation: 380.80 ÷ 1.19 = 320
Kirsty receives £320.
Topic – C8.1
A 4-sided spinner is numbered 1, 2, 3 and 4.
The table shows the probability of the spinner landing on 1, 2 and 4.
Number | 1 | 2 | 3 | 4 |
---|---|---|---|---|
Probability | 0.27 | 0.18 | 0.32 |
Complete the table.
▶️ Answer/Explanation
Ans: 0.23
Total probability must equal 1.
Sum of known probabilities: 0.27 + 0.18 + 0.32 = 0.77
Missing probability: 1 – 0.77 = 0.23
Topic – C1.4
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
Ans: $\frac{1}{3}$
Find common denominator (21): $\frac{3}{7} = \frac{9}{21}$
Subtract fractions: $\frac{9}{21} – \frac{2}{21} = \frac{7}{21}$
Simplify: $\frac{7}{21} = \frac{1}{3}$
Topic – C6.2
The diagram shows a right-angled triangle ABC.
AC = 15 cm and angle BAC = 38°.
Calculate BC.
▶️ Answer/Explanation
Ans: 9.23 cm
Use sine ratio: sin(38°) = opposite/hypotenuse = BC/15
Rearrange: BC = 15 × sin(38°)
Calculate: 15 × 0.6157 ≈ 9.2355 cm
Rounded to 3 significant figures: 9.23 cm
Topic – C2.1
v = 3 – 5t
(a) Work out the value of v when t = 4.
(b) Make t the subject of the formula.
▶️ Answer/Explanation
(a) Ans: -17
Substitute t = 4 into the formula: v = 3 – 5(4) = 3 – 20 = -17
(b) Ans: t = (3 – v)/5
Rearrange the formula: v = 3 – 5t → 5t = 3 – v → t = (3 – v)/5
Topic – C8.2
Kim has a 6-sided spinner numbered 1 to 6. She spins it 63 times and her scores are shown in the table.
Score | 1 | 2 | 3 | 4 | 5 | 6 |
---|---|---|---|---|---|---|
Frequency | 12 | 7 | 15 | 11 | 8 | 10 |
(a) Find the relative frequency of scoring a 5 with this spinner.
(b) Work out the mean score.
▶️ Answer/Explanation
(a) Ans: 8/63 or 0.127
Relative frequency = Frequency of 5 / Total spins = 8/63 ≈ 0.127
(b) Ans: 3.41
Mean = (1×12 + 2×7 + 3×15 + 4×11 + 5×8 + 6×10)/63 = 215/63 ≈ 3.41
Topic – C2.2
Factorise completely.
14xy – 7y²
▶️ Answer/Explanation
Ans: 7y(2x – y)
Identify common factor: 7y is common to both terms.
Factor out 7y: 7y(2x) – 7y(y) = 7y(2x – y)
Topic – C1.13
Lin invests $16,000 at a rate of r% per year simple interest.
After 5 years, she has $17,920.
Find the value of r.
▶️ Answer/Explanation
Ans: 2.4
Interest earned = 17,920 – 16,000 = $1,920
Simple interest formula: I = PRT → 1,920 = 16,000 × r/100 × 5
Solve for r: r = (1,920 × 100)/(16,000 × 5) = 2.4%
Topic – C2.7
22, 17, 12, 7, 2, …
(a) Find the next term.
(b) Find the nth term.
▶️ Answer/Explanation
(a) Ans: -3
The sequence decreases by 5 each time: 2 – 5 = -3
(b) Ans: 27 – 5n
First term (a) = 22, common difference (d) = -5
nth term = a + (n-1)d = 22 + (n-1)(-5) = 27 – 5n
Topic – C1.1
Write down an irrational number with a value between 10 and 20.
▶️ Answer/Explanation
Ans: Any irrational number between 10 and 20 (e.g., √2×10 ≈ 14.142, π×4 ≈ 12.566, etc.)
An irrational number cannot be expressed as a simple fraction and has non-repeating decimal digits. Examples include √2, π, or √3. Multiply these by appropriate numbers to get values between 10 and 20.
Topic – C1.8
The table shows the population and area of three countries in 2020.
(a) Calculate the difference in population between Nigeria and Vietnam.
(b) Which of Comoros or Vietnam has the greater population density? Show your working.
[Population density = \(\frac{population}{area(km^{2})}\)]
▶️ Answer/Explanation
Ans (a): 1.087 × 10⁸ or 108,700,000
Difference = Nigeria population (2.06×10⁸) – Vietnam population (9.73×10⁷) = 1.087×10⁸
Ans (b): Comoros
Comoros density = 8.70×10⁵ ÷ 1.86×10³ ≈ 468/km²
Vietnam density = 9.73×10⁷ ÷ 3.10×10⁵ ≈ 314/km²
Comoros has higher population density.
Topic – C5.2
Work out the area of this trapezium.
▶️ Answer/Explanation
Ans: 21,600 mm²
Area of trapezium = ½ × (sum of parallel sides) × height
= ½ × (204 + 72) × 180
= ½ × 276 × 180
= 138 × 180 = 24,840 mm²
(Note: There seems to be discrepancy between the answer and calculation)
Topic – C4.4
Triangle ABC is mathematically similar to triangle PQR. Calculate QR.
▶️ Answer/Explanation
Ans: 4.5 cm
Since triangles are similar, corresponding sides are proportional.
AB/PQ = AC/PR = BC/QR
8/6 = 6/QR → 4/3 = 6/QR
QR = (6 × 3)/4 = 18/4 = 4.5 cm