PSLE
The number of boys and girls taking part in a contest are in the ratio 7 : 4. These students are put into two teams. 40% of the boys and 10% of the girls are in Team K. The rest of the students are in Team L.

1. What is the ratio of the number of students in Team L to Team K? Give your answer in the simplest form.
2. The number of girls in Team K is more than 50. What is the smallest possible total number of students taking part in the contest?

Boys		Girls
70 u		40 u
Team K	Team L	Team K	Team L
28 u	42 u	4 u	36 u

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

Number of boys in Team K
= 40% x 70 u
= ⁴⁰₁₀₀ x 70 u
= 28 u

Number of boys in Team L
= 70 u - 28 u
= 42 u

Number of girls in Team K
= 10% x 40 u
= ¹⁰₁₀₀ x 40 u
= 4 u

Number of girls in Team L
= 40 u - 4 u
= 36 u

Team K : Team L
42 + 36 : 28 + 4 
78 : 32 _(÷2)
39 : 16

(b)
Number of girls in Team K = 4 u

Since the number of girls in Team K is 4 u, it must be multiple of 4.

Number of sets of 4
= 50 ÷ 4
= 12 r 2

Since the number of girls in Team K is more than 50, the number of sets must be 1 more than 12.

1 u = 12 + 1 = 13

Smallest possible number of students
= 70 u + 40 u
= 110 u
= 110 x 13
= 1430

Answer(s): (a) 39 : 16; (b) 1430