PSLE The number of boys and girls taking part in a test are in the ratio 4 : 7. These pupils are put into two teams. 10% of the boys and 30% of the girls are in Team F. The rest of the pupils are in Team G.
- What is the ratio of the number of pupils in Team G to Team F? Give your answer in the simplest form.
- The number of girls in Team F is more than 80. What is the smallest possible total number of pupils taking part in the test?
Boys |
Girls |
40 u |
70 u |
Team F |
Team G |
Team F |
Team G |
4 u |
36 u |
21 u |
49 u |
(a)
Boys : Girls
4 : 7
40 : 70
Number of boys in Team F
= 10% x 40 u
=
10100 x 40 u
= 4 u
Number of boys in Team G
= 40 u - 4 u
= 36 u
Number of girls in Team F
= 30% x 70 u
=
30100 x 70 u
= 21 u
Number of girls in Team G
= 70 u - 21 u
= 49 u
Team F : Team G
36 + 49 : 4 + 21
85 : 25
(÷5)17 : 5
(b)
Number of girls in Team F = 21 u
Since the number of girls in Team F is 21 u, it must be multiple of 21.
Number of sets of 21
= 80 ÷ 21
= 3 r 17
Since the number of girls in Team F is more than 80, the number of sets must be 1 more than 3.
1 u = 3 + 1 = 4
Smallest possible number of pupils
= 40 u + 70 u
= 110 u
= 110 x 4
= 440
Answer(s): (a) 17 : 5; (b) 440