PSLE
The number of boys and girls taking part in a contest are in the ratio 1 : 4. These pupils are put into two teams. 40% of the boys and 20% 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 50. What is the smallest possible total number of pupils taking part in the contest?

Boys		Girls
10 u		40 u
Team C	Team D	Team C	Team D
4 u	6 u	8 u	32 u

(a)
Boys : Girls
1 : 4
10 : 40

Number of boys in Team C
= 40% x 10 u
= ⁴⁰₁₀₀ x 10 u
= 4 u

Number of boys in Team D
= 10 u - 4 u
= 6 u

Number of girls in Team C
= 20% x 40 u
= ²⁰₁₀₀ x 40 u
= 8 u

Number of girls in Team D
= 40 u - 8 u
= 32 u

Team C : Team D
6 + 32 : 4 + 8 
38 : 12 _(÷2)
19 : 6

(b)
Number of girls in Team C = 8 u

Since the number of girls in Team C is 8 u, it must be multiple of 8.

Number of sets of 8
= 50 ÷ 8
= 6 r 2

Since the number of girls in Team C is more than 50, the number of sets must be 1 more than 6.

1 u = 6 + 1 = 7

Smallest possible number of pupils
= 10 u + 40 u
= 50 u
= 50 x 7
= 350

Answer(s): (a) 19 : 6; (b) 350