PSLE
The number of boys and girls taking part in a test are in the ratio 4 : 5. These students are put into two teams. 20% of the boys and 60% of the girls are in Team G. The rest of the students are in Team H.

1. What is the ratio of the number of students in Team H to Team G? Give your answer in the simplest form.
2. The number of boys in Team H is fewer than 70. What is the largest possible total number of students taking part in the test?

Boys		Girls
40 u		50 u
Team G	Team H	Team G	Team H
8 u	32 u	30 u	20 u

(a)
Boys : Girls
4 : 5
40 : 50

Number of boys in Team G
= 20% x 40 u
= ²⁰₁₀₀ x 40 u
= 8 u

Number of boys in Team H
= 40 u - 8 u
= 32 u

Number of girls in Team G
= 60% x 50 u
= ⁶⁰₁₀₀ x 50 u
= 30 u

Number of girls in Team H
= 50 u - 30 u
= 20 u

Team H : Team G
32 + 20 : 8 + 30
52 : 38 _(÷2)
26 : 19

(b)
Number of boys in Team H = 32 u

Since the number of boys in Team H is 32 u, it must be multiple of 32.

Number of sets of 32
= 70 ÷ 32
= 2 r 6

Since the number of boys in Team H is less than 70, the number of sets must be 2.

1 u = 2

Largest possible number of students
= 40 u + 50 u
= 90 u
= 90 x 2
= 180

Answer(s): (a) 26 : 19; (b) 180