Topic – C1.4
Write \(\frac{8}{10}\) as a decimal.
▶️ Answer/Explanation
Ans: 0.8
To convert \(\frac{8}{10}\) to a decimal, divide the numerator by the denominator.
8 ÷ 10 = 0.8
Topic – C1.16
Asha works in a café.
Her wage is calculated using the formula \( \text{wage} = \text{hourly rate} \times \text{number of hours} + \text{bonus} \).
Her hourly rate is $11.52.
One week Asha works 25 hours and receives a bonus of $5.40.
Work out her wage for this week.
▶️ Answer/Explanation
Ans: $293.40
Using the formula: wage = hourly rate × hours + bonus
= $11.52 × 25 + $5.40
= $288.00 + $5.40 = $293.40
Topic – C2.7
These are the first four terms in a sequence.
-3 4 11 18
(a) Find the next term.
(b) Explain how you worked out your answer.
▶️ Answer/Explanation
Ans: (a) 25 (b) Added 7
(a) Looking at the differences between terms: 4 – (-3) = 7, 11 – 4 = 7, 18 – 11 = 7
So the next term is 18 + 7 = 25
(b) The pattern is adding 7 each time.
Topic – C1.4
Work out \(\frac{2}{5}\) of 180.
▶️ Answer/Explanation
Ans: 72
To find \(\frac{2}{5}\) of 180:
First divide 180 by 5 to get \(\frac{1}{5}\): 180 ÷ 5 = 36
Then multiply by 2: 36 × 2 = 72
Topic – C1.5
Write these numbers in order, starting with the smallest:
\(\frac{3}{16}\), 18.7%, 0.19, \(\frac{9}{50}\)
▶️ Answer/Explanation
Ans: \(\frac{9}{50}\) < 18.7% < \(\frac{3}{16}\) < 0.19
Convert all to decimals: \(\frac{9}{50}\) = 0.18, 18.7% = 0.187, \(\frac{3}{16}\) ≈ 0.1875, 0.19
Order: 0.18, 0.187, 0.1875, 0.19
Topic – C1.6
Write down the number that is 9 greater than -23.
▶️ Answer/Explanation
Ans: -14
-23 + 9 = -14
Adding 9 moves the number 9 places to the right on the number line.
Topic – C9.4
For 16 days, Safia records the number of dresses she sells:
24, 6, 18, 14, 27, 37, 9, 16
22, 17, 16, 16, 24, 20, 15, 32
(a) Complete the stem-and-leaf diagram.
(b) Write down the mode.
(c) Find the median.
▶️ Answer/Explanation
Ans:
(a) Stem-and-leaf:
(b) Mode = 16 (appears most frequently)
(c) Median = (16+19)/2 = 17.5 (average of 8th and 9th values when ordered)
Topic – C1.10
Write 24.07839
(a) correct to 2 decimal places
(b) correct to the nearest 10
▶️ Answer/Explanation
Ans:
(a) 24.08 (look at 3rd decimal 8 ≥5, so round up)
(b) 20 (look at units digit 4 <5, so round down)
Topic – C2.5
Given v = u + at, find the value of v when u = 30, a = -2 and t = 7.
▶️ Answer/Explanation
Ans: 16
v = 30 + (-2)×7
v = 30 – 14
v = 16
Topic – C5.1
Change 62,000 millimetres into kilometres.
▶️ Answer/Explanation
Ans: 0.062 km
First convert mm to m: 62,000 ÷ 1,000 = 62 m
Then convert m to km: 62 ÷ 1,000 = 0.062 km
Topic – C4.6
The diagram shows two straight lines crossing two parallel lines. Find the value of x.
▶️ Answer/Explanation
Ans: 64
1. The angle adjacent to 114° is 66° (180° – 114°).
2. In the triangle formed, the third angle is 64° (180° – 50° – 66°).
3. x is equal to this angle because they are vertically opposite angles.
Markscheme:
B1 for any of these angles labelled on the diagram.
Topic – C1.1
(a) Explain why 111 is not a prime number.
(b) Find a prime number between 110 and 120.
▶️ Answer/Explanation
Ans: (a) It’s divisible by 3 (b) 113
(a) 111 is divisible by 3 (1+1+1=3, which is divisible by 3).
(b) Checking numbers between 110-120: 113 isn’t divisible by 2, 3, 5, 7, or 11, making it prime.
Topic – C4.6
Find the bearing of Q from P.
▶️ Answer/Explanation
Ans: 231°
1. The angle between North and the line PQ is 39°.
2. The bearing is measured clockwise from North.
3. 180° (South) + 90° (East) – 39° = 231°.
Topic – C9.5
(a) As the age of a car increases, the selling price decreases. What type of correlation is this?
(b) Write down the type of correlation between the height of a driver and the value of their car.
▶️ Answer/Explanation
Ans: (a) Negative (b) No correlation
(a) As one variable increases while the other decreases, this shows negative correlation.
(b) There’s no logical connection between a driver’s height and car value, so no correlation exists.
Topic – C4.6
Calculate the interior angle of a regular 9-sided polygon.
▶️ Answer/Explanation
Ans: 140°
1. Sum of interior angles = (9-2) × 180° = 1260°.
2. Each interior angle = 1260° ÷ 9 = 140°.
Alternatively: 180° – (360° ÷ 9) = 140°.
Topic – C1.13
Filip invests $4000 for 3 years at a rate of 2.5% per year simple interest.
Calculate the value of his investment at the end of the 3 years.
▶️ Answer/Explanation
Ans: $4300
First calculate the interest: $4000 × 2.5% × 3 = $300
Then add to principal: $4000 + $300 = $4300
Topic – C4.7
A, B and C are points on a circle, center O.
(a) Draw a tangent to the circle at point A.
(b) The circumference of the circle is 22.3 cm. Calculate the radius of the circle.
(c) Give a geometrical reason why angle BCA is 90°.
▶️ Answer/Explanation
Ans:
(a) A line perpendicular to radius OA at point A
(b) r = C/(2π) = 22.3/(2×3.142) ≈ 3.55 cm
(c) Angle in a semicircle is always 90°
Topic – C2.2
Expand and simplify.
2(t + w) + 3(w – t)
▶️ Answer/Explanation
Ans: 5w – t
First expand: 2t + 2w + 3w – 3t
Then combine like terms: (2t – 3t) + (2w + 3w)
Final simplification: -t + 5w or 5w – t
Topic – C1.4
Without using a calculator, work out 3⅛ – 1¾.
You must show all your working and give your answer as a mixed number in its simplest form.
▶️ Answer/Explanation
Ans: 1⅜
Convert to improper fractions: 25/8 – 7/4
Find common denominator: 25/8 – 14/8
Subtract: 11/8
Convert to mixed number: 1⅜
Topic – C1.2
ξ = {students in a class}
C = {students who play cricket}
F = {students who play football}
There are 36 students in the class.
15 students play cricket.
20 students play football.
(a) Complete the Venn diagram.
(b) Write down n(C ∪ F).
▶️ Answer/Explanation
Ans:
(a) Intersection: 15 + 20 – 36 = 11 (overlap), C only: 4, F only: 16
(b) n(C ∪ F) = 4 + 11 + 16 = 31 (all students who play either sport)
Topic – C6.2
ABC is a right-angled triangle.
Calculate AC.
▶️ Answer/Explanation
AC = 21.7 cm
Using cosine ratio: cos(34°) = adjacent/hypotenuse = BC/AC
cos(34°) = 18/AC
AC = 18/cos(34°)
AC ≈ 18/0.829 ≈ 21.7 cm
Topic – C3.1
Point A and line L are shown on the grid.
(a) Write down the coordinates of point A.
(b) On the grid, plot the point (-2, 4).
(c) Find the equation of line L.
▶️ Answer/Explanation
(a) (1, -2)
(b) Point plotted at (-2, 4)
(c) y = 2x + 3
For (a): Read directly from the grid.
For (c): The line passes through (0,3) giving y-intercept 3. The slope is 2 (rise/run = 2/1).
Topic – C1.6
Bell A rings every 22 minutes.
Bell B rings every 14 minutes.
Both bells ring at 09:00.
Work out the next time both bells ring together.
▶️ Answer/Explanation
11:34
Find LCM of 22 and 14 minutes.
Prime factors: 22 = 2×11, 14 = 2×7
LCM = 2×7×11 = 154 minutes
154 minutes = 2 hours 34 minutes
09:00 + 2:34 = 11:34
Topic – C4.4
Triangle ABC is mathematically similar to triangle DEF.
Calculate the value of x.
▶️ Answer/Explanation
x = 5.84 cm
Find the scale factor: DF/AB = 4.4/5.5 = 0.8
Apply to BC: x = 7.3 × 0.8 = 5.84 cm
Alternatively: x/7.3 = 4.4/5.5
x = (4.4 × 7.3)/5.5 = 5.84 cm