PSLE
The number of boys and girls taking part in a contest are in the ratio 4 : 7. These students are put into two teams. 50% of the boys and 40% 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 90. What is the smallest possible total number of students taking part in the contest?

Boys		Girls
40 u		70 u
Team U	Team V	Team U	Team V
20 u	20 u	28 u	42 u

(a)
Boys : Girls
4 : 7
40 : 70

Number of boys in Team U
= 50% x 40 u
= ⁵⁰₁₀₀ x 40 u
= 20 u

Number of boys in Team V
= 40 u - 20 u
= 20 u

Number of girls in Team U
= 40% x 70 u
= ⁴⁰₁₀₀ x 70 u
= 28 u

Number of girls in Team V
= 70 u - 28 u
= 42 u

Team U : Team V
20 + 42 : 20 + 28 
62 : 48 _(÷2)
31 : 24

(b)
Number of girls in Team U = 28 u

Since the number of girls in Team U is 28 u, it must be multiple of 28.

Number of sets of 28
= 90 ÷ 28
= 3 r 6

Since the number of girls in Team U is more than 90, the number of sets must be 1 more than 3.

1 u = 3 + 1 = 4

Smallest possible number of students
= 40 u + 70 u
= 110 u
= 110 x 4
= 440

Answer(s): (a) 31 : 24; (b) 440