PSLE
The number of girls and boys taking part in a contest are in the ratio 3 : 8. These pupils are put into two teams. 40% of the girls and 20% of the boys are in Team A. The rest of the pupils are in Team B.

1. What is the ratio of the number of pupils in Team B to Team A? Give your answer in the simplest form.
2. The number of boys in Team A is more than 40. What is the smallest possible total number of pupils taking part in the contest?

Girls		Boys
30 u		80 u
Team A	Team B	Team A	Team B
12 u	18 u	16 u	64 u

(a)
Girls : Boys
3 : 8
30 : 80

Number of girls in Team A
= 40% x 30 u
= ⁴⁰₁₀₀ x 30 u
= 12 u

Number of girls in Team B
= 30 u - 12 u
= 18 u

Number of boys in Team A
= 20% x 80 u
= ²⁰₁₀₀ x 80 u
= 16 u

Number of boys in Team B
= 80 u - 16 u
= 64 u

Team A : Team B
18 + 64 : 12 + 16 
82 : 28 _(÷2)
41 : 14

(b)
Number of boys in Team A = 16 u

Since the number of boys in Team A is 16 u, it must be multiple of 16.

Number of sets of 16
= 40 ÷ 16
= 2 r 8

Since the number of boys in Team A is more than 40, the number of sets must be 1 more than 2.

1 u = 2 + 1 = 3

Smallest possible number of pupils
= 30 u + 80 u
= 110 u
= 110 x 3
= 330

Answer(s): (a) 41 : 14; (b) 330