Module 2 · Answers
Answers & working
Workings shown so you can see where each answer comes from.
Section A — Easy
01
(a) 6.9 (b) 4.3 (c) 4.05 (d) 3.65
Line up decimal points. (c) 3.25 + 0.80 = 4.05. (d) 6.10 − 2.45 = 3.65.
02
(a) 0.06 (b) 0.28 (c) 0.30
Multiply digits, count decimal places. 3 × 2 = 6, 2 d.p. → 0.06.
03
(a) 30 (b) 8 (c) 30
Make divisor whole. (a) 60 ÷ 2 = 30. (b) 48 ÷ 6 = 8. (c) 90 ÷ 3 = 30.
04
y: 2, 3, 4, 5
05
Gradient = 3, y-intercept = −2
In y = mx + c, m is gradient and c is y-intercept.
06
C = 1.20m + 2.50
Section B — Medium
07
(a) 3.6 (b) 0.9 (c) 315
(a) 24 × 15 = 360, 2 d.p. → 3.60. (b) 36 × 25 = 900, 3 d.p. → 0.900. (c) 1260 ÷ 4 = 315.
08
8 pieces
4.8 ÷ 0.6 = 48 ÷ 6 = 8.
09
Points e.g. (0, −1), (1, 1), (2, 3). Gradient = 2, y-intercept = −1.
10
Gradient = 2
(10 − 4) ÷ (3 − 0) = 6 ÷ 3 = 2.
11
Speed = 45 mph. Straight line through origin, gradient 45.
90 ÷ 2 = 45 mph. Or 225 ÷ 5 = 45.
12
$80 ≈ £64
80 ÷ 1.25 = 64.
Section C — Hard
13
6.24
0.6 × 1.4 = 0.84.
2.16 ÷ 0.4 = 21.6 ÷ 4 = 5.4.
0.84 + 5.4 = 6.24.
2.16 ÷ 0.4 = 21.6 ÷ 4 = 5.4.
0.84 + 5.4 = 6.24.
14
m = 3, c = 2 (so y = 3x + 2)
m = (14 − 5) ÷ (4 − 1) = 9 ÷ 3 = 3.
5 = 3(1) + c, so c = 2.
5 = 3(1) + c, so c = 2.
15
(a) 6 L/min (b) 0 litres (c) V = 6t
Rate = (150 − 60) ÷ (25 − 10) = 90 ÷ 15 = 6 L/min.
At t = 10, V = 60, so 60 = 6(10) + c, c = 0.
At t = 10, V = 60, so 60 = 6(10) + c, c = 0.
16
200 minutes
10 + 0.05m = 4 + 0.08m
6 = 0.03m
m = 200.
6 = 0.03m
m = 200.