PSLE
The number of girls and boys taking part in a quiz are in the ratio 2 : 7. These pupils are put into two teams. 30% of the girls and 40% of the boys are in Team G. The rest of the pupils are in Team H.

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

Girls		Boys
20 u		70 u
Team G	Team H	Team G	Team H
6 u	14 u	28 u	42 u

(a)
Girls : Boys
2 : 7
20 : 70

Number of girls in Team G
= 30% x 20 u
= ³⁰₁₀₀ x 20 u
= 6 u

Number of girls in Team H
= 20 u - 6 u
= 14 u

Number of boys in Team G
= 40% x 70 u
= ⁴⁰₁₀₀ x 70 u
= 28 u

Number of boys in Team H
= 70 u - 28 u
= 42 u

Team H : Team G
14 + 42 : 6 + 28
56 : 34 _(÷2)
28 : 17

(b)
Number of girls in Team H = 14 u

Since the number of girls in Team H is 14 u, it must be multiple of 14.

Number of sets of 14
= 90 ÷ 14
= 6 r 6

Since the number of girls in Team H is less than 90, the number of sets must be 6.

1 u = 6

Largest possible number of pupils
= 20 u + 70 u
= 90 u
= 90 x 6
= 540

Answer(s): (a) 28 : 17; (b) 540