Module 4 · Answers
Answers & working
Workings shown so you can see where each answer comes from.
Section A — Easy
01
(a) 3/10 (b) 8/21 (c) 2/3
(c) 3/4 × 8/9 = 24/36 = 2/3 (cancel 12).
02
(a) 2 (b) 5/6 (c) 3/4
Keep, change, flip. (b) 2/3 × 5/4 = 10/12 = 5/6.
03
(a) 20 (b) 6.5 (c) 12
04
£44
40 × 1.10 = 44.
05
£120
150 × 0.80 = 120.
06
(a) 1.12 (b) 0.93 (c) 1.35
Section B — Medium
07
(a) 4 3/8 (b) 8 1/3
(a) 5/2 × 7/4 = 35/8 = 4 3/8.
(b) 10/3 ÷ 2/5 = 10/3 × 5/2 = 50/6 = 25/3 = 8 1/3.
(b) 10/3 ÷ 2/5 = 10/3 × 5/2 = 50/6 = 25/3 = 8 1/3.
08
£45
250 × 0.18 = 45.
09
£52
80 × 0.65 = 52.
10
15%
Profit = 27 000. % = 27 000 ÷ 180 000 × 100 = 15.
11
25%
Decrease = 240. % = 240 ÷ 960 × 100 = 25.
12
40 biscuits
3/8 eaten ⇒ 5/8 remain = 25. Total = 25 ÷ 5 × 8 = 40.
Section C — Hard
13
No — overall change is a 4% decrease.
Multiplier: 1.20 × 0.80 = 0.96 → 4% lower.
14
£24 000
Old × 1.15 = 27 600.
Old = 27 600 ÷ 1.15 = 24 000.
Old = 27 600 ÷ 1.15 = 24 000.
15
1/2
2/3 + 1/4 = 8/12 + 3/12 = 11/12.
11/12 × 6/11 = 66/132 = 1/2.
11/12 × 6/11 = 66/132 = 1/2.
16
£48
Cost × 1.25 × 0.75 = 45
Cost × 0.9375 = 45
Cost = 45 ÷ 0.9375 = 48.
Cost × 0.9375 = 45
Cost = 45 ÷ 0.9375 = 48.