Page 34 - ACE YR IGCSE A TOP APPR' TO MATHS

3 Let x = 0.807 k = 55
1000x = 807.807 t = 55
999x = 807 200
x = 807 = 269 = 0.275 min [2]
999 333 [2] 6 Weight of book = W
4 9.16 = 9 + 0.16 Number of pages = N
Let x = 0.16 W = kN
10x = 1.6 0.08 = k(50)
100x = 16.6 k = 0.0016
90x = 15 w = 0.0016(720)
x = 15 =1.152 kg [2]
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90 7 m = kh
9.16 = 9 + 15 131.25 = k(12.5)
= 9 1 90 k = 10.5
6 [2] m = 10.5(11 × 25)
5 2.534 = 2 + 0.534 = $2887.5 [2]
Let x = 0.534 8 Number of months = M
10x = 5.34 Number of workers = W
1000x = 534.34 k
990x = 529 M = w
x = 529 5 = k
990 10
2.534 = 2 + 529 = 2 529 k = 50
50
990 990 [2] M = 20
= 2.5 months [2]
Direct and inverse proportion
9 Number of days =
1 A = kB 2 Amount of time (in hours) = T
300 = k(10) D = k
2
k = 3 T
(a) A = 3B 2 [2] 150 = k
( ) 2 3 0.5
1
(b) A = 3 2 = 4 [2] k = 75
D = 75
2 r = k√s + 2 1.25
5√5 = k√3 + 2 = 60 days [2]
k = 5
r = 5√7 + 2 Fractions
=15 [2]
1 (a) 3 6 + 1 7 = 4 13 (shown) [2]
3 A = k(B + 3B – 4) 21 21 21
2
7 = k(3 + 3(3) – 4) (b) 249 − 200 = 49 = 1 19 (shown) [2]
2
k = 1 30 30 30 30
2 2 11 − 1 × 1
–2 = 1 (B + 3B – 4) 4 6 2
2
2 11 1
B(B + 3) = 0 = 4 − 12
B = 0 or B = –3 [2] 33 – 1
=
4 = km 12
0.96 = k(1.2) = 32
k = 0.8 12
5 = 0.8m 8 2
m = 6.25 kg [2] = 3 or 2 3 [2]
k
5 t = p 3 11 × 4

0.25 = k 6 22 3
220 =
9

Cambridge IGCSE
TM
154 Ace Your Mathematics

Answers.indd 154 15/03/2022 11:08 AM