PSLE
The number of boys and girls taking part in a quiz are in the ratio 2 : 5. These students are put into two teams. 80% of the boys and 10% of the girls are in Team F. The rest of the students are in Team G.

1. What is the ratio of the number of students in Team G to Team F? Give your answer in the simplest form.
2. The number of boys in Team G is fewer than 70. What is the largest possible total number of students taking part in the quiz?

Boys		Girls
20 u		50 u
Team F	Team G	Team F	Team G
16 u	4 u	5 u	45 u

(a)
Boys : Girls
2 : 5
20 : 50

Number of boys in Team F
= 80% x 20 u
= ⁸⁰₁₀₀ x 20 u
= 16 u

Number of boys in Team G
= 20 u - 16 u
= 4 u

Number of girls in Team F
= 10% x 50 u
= ¹⁰₁₀₀ x 50 u
= 5 u

Number of girls in Team G
= 50 u - 5 u
= 45 u

Team G : Team F
4 + 45 : 16 + 5
49 : 21 _(÷7)
7 : 3

(b)
Number of boys in Team G = 4 u

Since the number of boys in Team G is 4 u, it must be multiple of 4.

Number of sets of 4
= 70 ÷ 4
= 17 r 2

Since the number of boys in Team G is less than 70, the number of sets must be 17.

1 u = 17

Largest possible number of students
= 20 u + 50 u
= 70 u
= 70 x 17
= 1190

Answer(s): (a) 7 : 3; (b) 1190