PSLE
The number of boys and girls taking part in a test are in the ratio 1 : 3. These students are put into two teams. 80% of the boys and 20% of the girls are in Team D. The rest of the students are in Team E.

1. What is the ratio of the number of students in Team E to Team D? Give your answer in the simplest form.
2. The number of girls in Team D is more than 40. What is the smallest possible total number of students taking part in the test?

Boys		Girls
10 u		30 u
Team D	Team E	Team D	Team E
8 u	2 u	6 u	24 u

(a)
Boys : Girls
1 : 3
10 : 30

Number of boys in Team D
= 80% x 10 u
= ⁸⁰₁₀₀ x 10 u
= 8 u

Number of boys in Team E
= 10 u - 8 u
= 2 u

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

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

Team D : Team E
2 + 24 : 8 + 6 
26 : 14 _(÷2)
13 : 7

(b)
Number of girls in Team D = 6 u

Since the number of girls in Team D is 6 u, it must be multiple of 6.

Number of sets of 6
= 40 ÷ 6
= 6 r 4

Since the number of girls in Team D is more than 40, the number of sets must be 1 more than 6.

1 u = 6 + 1 = 7

Smallest possible number of students
= 10 u + 30 u
= 40 u
= 40 x 7
= 280

Answer(s): (a) 13 : 7; (b) 280