PSLE
The number of boys and girls taking part in a quiz are in the ratio 5 : 4. These students are put into two teams. 30% of the boys and 50% 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 girls in Team K is more than 50. What is the smallest possible total number of students taking part in the quiz?

Boys		Girls
50 u		40 u
Team K	Team L	Team K	Team L
15 u	35 u	20 u	20 u

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

Number of boys in Team K
= 30% x 50 u
= ³⁰₁₀₀ x 50 u
= 15 u

Number of boys in Team L
= 50 u - 15 u
= 35 u

Number of girls in Team K
= 50% x 40 u
= ⁵⁰₁₀₀ x 40 u
= 20 u

Number of girls in Team L
= 40 u - 20 u
= 20 u

Team K : Team L
35 + 20 : 15 + 20 
55 : 35 _(÷5)
11 : 7

(b)
Number of girls in Team K = 20 u

Since the number of girls in Team K is 20 u, it must be multiple of 20.

Number of sets of 20
= 50 ÷ 20
= 2 r 10

Since the number of girls in Team K is more than 50, the number of sets must be 1 more than 2.

1 u = 2 + 1 = 3

Smallest possible number of students
= 50 u + 40 u
= 90 u
= 90 x 3
= 270

Answer(s): (a) 11 : 7; (b) 270