PSLE
The number of boys and girls taking part in a test are in the ratio 3 : 2. These pupils are put into two teams. 10% of the boys and 60% of the girls are in Team C. The rest of the pupils are in Team D.

1. What is the ratio of the number of pupils in Team D to Team C? Give your answer in the simplest form.
2. The number of girls in Team C is more than 40. What is the smallest possible total number of pupils taking part in the test?

Boys		Girls
30 u		20 u
Team C	Team D	Team C	Team D
3 u	27 u	12 u	8 u

(a)
Boys : Girls
3 : 2
30 : 20

Number of boys in Team C
= 10% x 30 u
= ¹⁰₁₀₀ x 30 u
= 3 u

Number of boys in Team D
= 30 u - 3 u
= 27 u

Number of girls in Team C
= 60% x 20 u
= ⁶⁰₁₀₀ x 20 u
= 12 u

Number of girls in Team D
= 20 u - 12 u
= 8 u

Team C : Team D
27 + 8 : 3 + 12 
35 : 15 _(÷5)
7 : 3

(b)
Number of girls in Team C = 12 u

Since the number of girls in Team C is 12 u, it must be multiple of 12.

Number of sets of 12
= 40 ÷ 12
= 3 r 4

Since the number of girls in Team C is more than 40, the number of sets must be 1 more than 3.

1 u = 3 + 1 = 4

Smallest possible number of pupils
= 30 u + 20 u
= 50 u
= 50 x 4
= 200

Answer(s): (a) 7 : 3; (b) 200