PSLE
The number of girls and boys taking part in a test are in the ratio 3 : 7. These students are put into two teams. 60% of the girls and 20% of the boys are in Team N. The rest of the students are in Team P.

1. What is the ratio of the number of students in Team P to Team N? Give your answer in the simplest form.
2. The number of boys in Team N is more than 90. What is the smallest possible total number of students taking part in the test?

Girls		Boys
30 u		70 u
Team N	Team P	Team N	Team P
18 u	12 u	14 u	56 u

(a)
Girls : Boys
3 : 7
30 : 70

Number of girls in Team N
= 60% x 30 u
= ⁶⁰₁₀₀ x 30 u
= 18 u

Number of girls in Team P
= 30 u - 18 u
= 12 u

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

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

Team N : Team P
12 + 56 : 18 + 14 
68 : 32 _(÷4)
17 : 8

(b)
Number of boys in Team N = 14 u

Since the number of boys in Team N is 14 u, it must be multiple of 14.

Number of sets of 14
= 90 ÷ 14
= 6 r 6

Since the number of boys in Team N is more than 90, the number of sets must be 1 more than 6.

1 u = 6 + 1 = 7

Smallest possible number of students
= 30 u + 70 u
= 100 u
= 100 x 7
= 700

Answer(s): (a) 17 : 8; (b) 700