PSLE
The number of girls and boys taking part in a test are in the ratio 3 : 2. These students are put into two teams. 20% of the girls and 40% of the boys are in Team L. The rest of the students are in Team M.

1. What is the ratio of the number of students in Team M to Team L? Give your answer in the simplest form.
2. The number of girls in Team M is fewer than 90. What is the largest possible total number of students taking part in the test?

Girls		Boys
30 u		20 u
Team L	Team M	Team L	Team M
6 u	24 u	8 u	12 u

(a)
Girls : Boys
3 : 2
30 : 20

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

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

Number of boys in Team L
= 40% x 20 u
= ⁴⁰₁₀₀ x 20 u
= 8 u

Number of boys in Team M
= 20 u - 8 u
= 12 u

Team M : Team L
24 + 12 : 6 + 8
36 : 14 _(÷2)
18 : 7

(b)
Number of girls in Team M = 24 u

Since the number of girls in Team M is 24 u, it must be multiple of 24.

Number of sets of 24
= 90 ÷ 24
= 3 r 18

Since the number of girls in Team M is less than 90, the number of sets must be 3.

1 u = 3

Largest possible number of students
= 30 u + 20 u
= 50 u
= 50 x 3
= 150

Answer(s): (a) 18 : 7; (b) 150