PSLE
The number of girls and boys taking part in a contest are in the ratio 2 : 7. These students are put into two teams. 30% of the girls and 20% of the boys are in Team G. The rest of the students are in Team H.

1. What is the ratio of the number of students in Team H to Team G? Give your answer in the simplest form.
2. The number of girls in Team H is fewer than 50. What is the largest possible total number of students taking part in the contest?

Girls		Boys
20 u		70 u
Team G	Team H	Team G	Team H
6 u	14 u	14 u	56 u

(a)
Girls : Boys
2 : 7
20 : 70

Number of girls in Team G
= 30% x 20 u
= ³⁰₁₀₀ x 20 u
= 6 u

Number of girls in Team H
= 20 u - 6 u
= 14 u

Number of boys in Team G
= 20% x 70 u
= ²⁰₁₀₀ x 70 u
= 14 u

Number of boys in Team H
= 70 u - 14 u
= 56 u

Team H : Team G
14 + 56 : 6 + 14
70 : 20 _(÷10)
7 : 2

(b)
Number of girls in Team H = 14 u

Since the number of girls in Team H is 14 u, it must be multiple of 14.

Number of sets of 14
= 50 ÷ 14
= 3 r 8

Since the number of girls in Team H is less than 50, the number of sets must be 3.

1 u = 3

Largest possible number of students
= 20 u + 70 u
= 90 u
= 90 x 3
= 270

Answer(s): (a) 7 : 2; (b) 270