PSLE
The number of boys and girls taking part in a test are in the ratio 8 : 5. These pupils are put into two teams. 50% of the boys and 30% of the girls are in Team E. The rest of the pupils are in Team F.

1. What is the ratio of the number of pupils in Team F to Team E? Give your answer in the simplest form.
2. The number of girls in Team E is more than 70. What is the smallest possible total number of pupils taking part in the test?

Boys		Girls
80 u		50 u
Team E	Team F	Team E	Team F
40 u	40 u	15 u	35 u

(a)
Boys : Girls
8 : 5
80 : 50

Number of boys in Team E
= 50% x 80 u
= ⁵⁰₁₀₀ x 80 u
= 40 u

Number of boys in Team F
= 80 u - 40 u
= 40 u

Number of girls in Team E
= 30% x 50 u
= ³⁰₁₀₀ x 50 u
= 15 u

Number of girls in Team F
= 50 u - 15 u
= 35 u

Team E : Team F
40 + 35 : 40 + 15 
75 : 55 _(÷5)
15 : 11

(b)
Number of girls in Team E = 15 u

Since the number of girls in Team E is 15 u, it must be multiple of 15.

Number of sets of 15
= 70 ÷ 15
= 4 r 10

Since the number of girls in Team E is more than 70, the number of sets must be 1 more than 4.

1 u = 4 + 1 = 5

Smallest possible number of pupils
= 80 u + 50 u
= 130 u
= 130 x 5
= 650

Answer(s): (a) 15 : 11; (b) 650