PSLE
The number of girls and boys taking part in a test are in the ratio 5 : 7. These pupils are put into two teams. 40% of the girls and 20% of the boys are in Team J. The rest of the pupils are in Team K.

1. What is the ratio of the number of pupils in Team K to Team J? Give your answer in the simplest form.
2. The number of girls in Team K is fewer than 80. What is the largest possible total number of pupils taking part in the test?

Girls		Boys
50 u		70 u
Team J	Team K	Team J	Team K
20 u	30 u	14 u	56 u

(a)
Girls : Boys
5 : 7
50 : 70

Number of girls in Team J
= 40% x 50 u
= ⁴⁰₁₀₀ x 50 u
= 20 u

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

Number of boys in Team J
= 20% x 70 u
= ²⁰₁₀₀ x 70 u
= 14 u

Number of boys in Team K
= 70 u - 14 u
= 56 u

Team K : Team J
30 + 56 : 20 + 14
86 : 34 _(÷2)
43 : 17

(b)
Number of girls in Team K = 30 u

Since the number of girls in Team K is 30 u, it must be multiple of 30.

Number of sets of 30
= 80 ÷ 30
= 2 r 20

Since the number of girls in Team K is less than 80, the number of sets must be 2.

1 u = 2

Largest possible number of pupils
= 50 u + 70 u
= 120 u
= 120 x 2
= 240

Answer(s): (a) 43 : 17; (b) 240