PSLE
The number of boys and girls taking part in a test are in the ratio 3 : 5. These students are put into two teams. 10% of the boys and 30% of the girls are in Team U. The rest of the students are in Team V.

1. What is the ratio of the number of students in Team V to Team U? Give your answer in the simplest form.
2. The number of girls in Team U is more than 80. What is the smallest possible total number of students taking part in the test?

Boys		Girls
30 u		50 u
Team U	Team V	Team U	Team V
3 u	27 u	15 u	35 u

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

Number of boys in Team U
= 10% x 30 u
= ¹⁰₁₀₀ x 30 u
= 3 u

Number of boys in Team V
= 30 u - 3 u
= 27 u

Number of girls in Team U
= 30% x 50 u
= ³⁰₁₀₀ x 50 u
= 15 u

Number of girls in Team V
= 50 u - 15 u
= 35 u

Team U : Team V
27 + 35 : 3 + 15 
62 : 18 _(÷2)
31 : 9

(b)
Number of girls in Team U = 15 u

Since the number of girls in Team U is 15 u, it must be multiple of 15.

Number of sets of 15
= 80 ÷ 15
= 5 r 5

Since the number of girls in Team U is more than 80, the number of sets must be 1 more than 5.

1 u = 5 + 1 = 6

Smallest possible number of students
= 30 u + 50 u
= 80 u
= 80 x 6
= 480

Answer(s): (a) 31 : 9; (b) 480