Topic – C1.6
Write 6475 correct to the nearest ten.
▶️ Answer/Explanation
Ans: 6480
Look at the units digit (5). Since it’s 5 or greater, we round the tens digit (7) up to 8.
Replace the units digit with 0 to get 6480.
Topic – C1.4
Write 0.75 as a fraction.
▶️ Answer/Explanation
Ans: 75/100 or equivalent
0.75 means 75 hundredths.
Write as 75/100 which can be simplified to 3/4.
Topic – C1.6
A piece of string has length 65.1 cm. The string is cut into 7 equal pieces.
Find the length of each piece.
▶️ Answer/Explanation
Ans: 9.3 cm
Divide total length by number of pieces: 65.1 ÷ 7 = 9.3
Each piece will be 9.3 cm long.
Topic – C9.3
Find the mode of these numbers.
▶️ Answer/Explanation
Ans: 12
Count how many times each number appears:
7 appears 2 times, 12 appears 3 times, others appear once.
12 appears most frequently, so it’s the mode.
Topic – C8.1
A bag contains 6 red balls, 4 green balls and 2 blue balls. Zia takes a ball from the bag at random.
Write down the letter from the probability scale that shows the probability that
(a) Zia takes a green ball
(b) Zia takes a yellow ball
(c) Zia does not take a blue ball
▶️ Answer/Explanation
Ans:
(a) C – Probability of green = 4/12 = 1/3
(b) A – No yellow balls, so probability = 0
(c) F – Probability of not blue = (6+4)/12 = 10/12 = 5/6
Total balls = 6 red + 4 green + 2 blue = 12
Topic – C2.7
These are the first four terms of a sequence.
19 26 33 40
(a) (i) Find the next term.
(ii) Write down the term to term rule for this sequence.
(b) These are the first four terms of another sequence.
-1 2 5 8
Find the nth term of this sequence.
▶️ Answer/Explanation
6(a)(i) Ans: 47
The sequence increases by 7 each time: 40 + 7 = 47
6(a)(ii) Ans: Add 7
Each term is 7 more than the previous term.
6(b) Ans: 3n – 4
Difference between terms is +3.
0th term would be -4 (as -1 = 3×1 – 4)
So nth term formula is 3n – 4
Topic – C2.2
Simplify: \( 3p – t – p – 4t \)
▶️ Answer/Explanation
Ans: \( 2p – 5t \)
Combine like terms:
\( 3p – p = 2p \)
\( -t – 4t = -5t \)
Final simplified form: \( 2p – 5t \)
Topic – C1.3
From the list of numbers, write down
(a) A cube number
(b) A prime number
▶️ Answer/Explanation
8(a) Ans: 64
4³ = 64, which is in the list.
8(b) Ans: 61 or 67
These numbers have no divisors other than 1 and themselves.
61 and 67 are both prime numbers from the list.
Topic – C4.3
The scale drawing shows the positions of town K and town L (scale: 1 cm represents 10 km).
(a) Find the actual distance between town K and town L.
(b) Measure the bearing of town L from town K.
(c) Town M is 40 km from town L on a bearing of 140°. On the scale drawing, mark the position of town M.
▶️ Answer/Explanation
9(a) Ans: 85 km
From the diagram, distance is 8.5 cm.
8.5 cm × 10 km/cm = 85 km
9(b) Ans: 065°
Measure the angle clockwise from north at K to the line KL.
9(c) 4 cm from L (since 40 km ÷ 10 km/cm = 4 cm)
At 140° bearing from L
Topic – C5.4
The surface area of a cube is 121.5 cm². Calculate the length of one side of the cube.
▶️ Answer/Explanation
Ans: 4.5 cm
A cube has 6 equal faces.
First find area of one face: 121.5 ÷ 6 = 20.25 cm²
Then take square root to find side length: √20.25 = 4.5 cm
Topic – C4.6
(a)
The diagram shows three lines meeting at a point.
Find the value of w.
(b)
BCD is an isosceles triangle. ABC is a straight line.
Find the value of y.
▶️ Answer/Explanation
Ans: (a) 190 (b) 130
(a) Angles around a point sum to 360°, so w = 360 – 80 – 90 – 90 = 190°
(b) Base angles of isosceles triangle BCD are equal. Angle BCD = (180-80)/2 = 50°. Then y = 180 – 50 = 130° (angles on straight line ABC).
Topic – C3.6
Write down the equation of a line parallel to the line y = 2x.
▶️ Answer/Explanation
Ans: y = 2x + k (where k is any constant ≠ 0)
Parallel lines have the same gradient. The original line has gradient 2, so any line of form y = 2x + k (where k is a constant) will be parallel.
Topic – C9.3
Each student in a class of 20 students records the number of coins in their pockets.
The table shows the results.
(a) Find the median.
(b) Calculate the mean.
▶️ Answer/Explanation
Ans: (a) 2 (b) 2.25
(a) With 20 students, median is average of 10th and 11th values when ordered. Both fall in the ‘2 coins’ group.
(b) Mean = (0×3 + 1×1 + 2×7 + 3×8 + 6×1)/20 = (0+1+14+24+6)/20 = 45/20 = 2.25
Topic – C2.2
Expand (x – 4)3.
▶️ Answer/Explanation
Ans: 4x – 12
Multiply each term inside the brackets by 3: 3 × x = 3x and 3 × (-4) = -12. Combine to get 3x – 12.
Topic – C4.5
Find the size of an interior angle of a regular 15-sided polygon.
▶️ Answer/Explanation
Ans: 156°
For any n-sided polygon, interior angle = (n-2)×180°/n. Here, (15-2)×180/15 = 13×12 = 156°.
Topic – C2.5
Rio buys some pens. He sells 63 pens, which is \(\frac{7}{9}\) of the pens he buys.
Work out how many pens he buys.
▶️ Answer/Explanation
Ans: 81
Let total pens be x.
\(\frac{7}{9}x = 63\)
\(x = 63 \times \frac{9}{7}\)
\(x = 81\) pens
Topic – C2.5
Ed has \(n\) books. Sam has 3 times as many books as Ed. Jane has 2 books fewer than Sam. The total number of books is 54.
Find the value of \(n\).
▶️ Answer/Explanation
Ans: 8
Ed: \(n\), Sam: \(3n\), Jane: \(3n-2\)
Total: \(n + 3n + 3n – 2 = 54\)
\(7n – 2 = 54\)
\(7n = 56\) → \(n = 8\)
Topic – C1.4
Without using a calculator, work out \(2\frac{1}{4} – 1\frac{11}{12}\).
Give your answer as a fraction in its simplest form.
▶️ Answer/Explanation
Ans: \(\frac{1}{3}\)
Convert to improper fractions: \(\frac{9}{4} – \frac{23}{12}\)
Common denominator (12): \(\frac{27}{12} – \frac{23}{12}\)
Subtract: \(\frac{4}{12}\)
Simplify: \(\frac{1}{3}\)
Topic – C1.2
ξ = {workers in an office}
C = {workers who drink coffee}
T = {workers who drink tea}
47 people work in the office. 32 people drink tea.
(a) Complete the Venn diagram
(b) Write down n(C ∪ T)
(c) Find probability a random worker doesn’t drink coffee
▶️ Answer/Explanation
Ans: (a) See completed diagram (b) 26 (c) \(\frac{14}{47}\)
(a) Coffee only: 47 – 32 – 8 = 7
Tea only: 32 – 6 = 26
(b) n(C ∪ T) = n(C) + n(T) – n(C ∩ T) = 7 + 32 – 6 = 26
(c) Doesn’t drink coffee: 26 (tea only) + 8 (neither) = 34 → \(\frac{34}{47}\)
Wait – mark scheme shows \(\frac{14}{47}\), meaning probability DOES drink coffee is \(\frac{33}{47}\), so doesn’t drink is \(\frac{14}{47}\)
Therefore: Coffee drinkers = 7 (only) + 6 (both) = 13
Non-coffee drinkers = 47 – 13 = 34? Doesn’t match mark scheme
Looking back: Mark scheme shows C=33 (7+26), but this seems inconsistent
Most likely correct answer per mark scheme: (c) \(\frac{14}{47}\)
Topic – C1.10
The weight, \(w\) grams, of a box is 463.9 grams, correct to 1 decimal place.
Complete the statement about the value of \(w\): …… ≤ \(w\) < ……
▶️ Answer/Explanation
Ans: 463.85 ≤ \(w\) < 463.95
To 1 decimal place, 463.9 means:
Lower bound: 463.85 (rounds up to 463.9)
Upper bound: 463.95 (rounds up to 464.0)
So \(w\) must be ≥463.85 and <463.95
Topic – C1.8
Calculate $(6.4 \times 10^5) \div (2.5 \times 10^{-7})$. Give your answer in standard form.
▶️ Answer/Explanation
Ans: 2.56 × 1012
First divide the numbers: 6.4 ÷ 2.5 = 2.56
Then handle the powers: 105 ÷ 10-7 = 105-(-7) = 1012
Combine them to get 2.56 × 1012
Topic – C1.13
Mia invests $1270 for 5 years at a rate of 2.1% per year compound interest. Calculate the value of her investment at the end of the 5 years.
▶️ Answer/Explanation
Ans: $1409.07
Use the compound interest formula: A = P(1 + r/100)n
A = 1270(1 + 0.021)5
Calculate 1.0215 ≈ 1.1095
Multiply: 1270 × 1.1095 ≈ 1409.07
Topic – C6.2
The diagram shows a right-angled triangle with angle 42° and hypotenuse 9.7 cm.
Calculate the value of x.
▶️ Answer/Explanation
Ans: 6.49 cm
Use the sine formula: sin(θ) = opposite/hypotenuse
sin(42°) = x/9.7
Rearrange: x = 9.7 × sin(42°)
Calculate: x ≈ 9.7 × 0.6691 ≈ 6.49 cm
Topic – C4.4
Shape A is mathematically similar to shape B.
Calculate the value of x.
▶️ Answer/Explanation
Ans: 8 cm
Find the scale factor: 6.75 ÷ 2.7 = 2.5
Apply to the other side: x = 3.2 × 2.5
Calculate: x = 8 cm
Alternatively: 3.2/x = 2.7/6.75 → x = (3.2 × 6.75)/2.7 = 8