PSLE
The number of boys and girls taking part in a contest are in the ratio 5 : 3. These students are put into two teams. 60% of the boys and 20% of the girls are in Team K. The rest of the students are in Team L.

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

Boys		Girls
50 u		30 u
Team K	Team L	Team K	Team L
30 u	20 u	6 u	24 u

(a)
Boys : Girls
5 : 3
50 : 30

Number of boys in Team K
= 60% x 50 u
= ⁶⁰₁₀₀ x 50 u
= 30 u

Number of boys in Team L
= 50 u - 30 u
= 20 u

Number of girls in Team K
= 20% x 30 u
= ²⁰₁₀₀ x 30 u
= 6 u

Number of girls in Team L
= 30 u - 6 u
= 24 u

Team L : Team K
20 + 24 : 30 + 6
44 : 36 _(÷4)
11 : 9

(b)
Number of boys in Team L = 20 u

Since the number of boys in Team L is 20 u, it must be multiple of 20.

Number of sets of 20
= 70 ÷ 20
= 3 r 10

Since the number of boys in Team L is less than 70, the number of sets must be 3.

1 u = 3

Largest possible number of students
= 50 u + 30 u
= 80 u
= 80 x 3
= 240

Answer(s): (a) 11 : 9; (b) 240