PSLE
The number of boys and girls taking part in a quiz are in the ratio 1 : 6. These pupils are put into two teams. 20% of the boys and 50% of the girls are in Team F. The rest of the pupils are in Team G.

1. What is the ratio of the number of pupils in Team G to Team F? Give your answer in the simplest form.
2. The number of boys in Team G is fewer than 90. What is the largest possible total number of pupils taking part in the quiz?

Boys		Girls
10 u		60 u
Team F	Team G	Team F	Team G
2 u	8 u	30 u	30 u

(a)
Boys : Girls
1 : 6
10 : 60

Number of boys in Team F
= 20% x 10 u
= ²⁰₁₀₀ x 10 u
= 2 u

Number of boys in Team G
= 10 u - 2 u
= 8 u

Number of girls in Team F
= 50% x 60 u
= ⁵⁰₁₀₀ x 60 u
= 30 u

Number of girls in Team G
= 60 u - 30 u
= 30 u

Team G : Team F
8 + 30 : 2 + 30
38 : 32 _(÷2)
19 : 16

(b)
Number of boys in Team G = 8 u

Since the number of boys in Team G is 8 u, it must be multiple of 8.

Number of sets of 8
= 90 ÷ 8
= 11 r 2

Since the number of boys in Team G is less than 90, the number of sets must be 11.

1 u = 11

Largest possible number of pupils
= 10 u + 60 u
= 70 u
= 70 x 11
= 770

Answer(s): (a) 19 : 16; (b) 770