PSLE
On Saturday, the number of adults to boys to girls visiting a safari park was 3 : 2 : 2. On Sunday, the number of adults visiting the safari park remained the same. However, the number of boys decreased by 50% and the number of girls increased by 50%.

1. What was the ratio of the number of children to adults visiting the safari park on Sunday?
2. On Saturday, 168 boys and girls visited the safari park. What was the total number of child visitors at the safari park on Sunday?

	Adults	Boys	Girls
Before	3 u	2 u	2 u
Change		- 1 u	+ 1 u
After	3 u	1 u	3 u

(a)
Increase in the number of boys
= 50% x 2 u
= ⁵⁰₁₀₀ x 2 u
= 1 u

Decrease in the number of girls
= 50% x 2 u
= ⁵⁰₁₀₀ x 2 u
= 1 u

Number of boys on Sunday
= 2 u - 1 u
= 1 u

Number of girls on Sunday
= 2 u + 1 u
= 3 u

Number of children on Sunday
= 1 u + 3 u
= 4 u

On Sunday
Children : Adults
4 : 3

(b)
Number of boys and girls on Saturday
= 2 u + 2 u
= 4 u

4 u = 168

1 u = 168 ÷ 4 = 42

Total number of child visitors on Sunday
= 4 u
= 4 x 42
= 168

Answer(s): (a) 4 : 3; (b) 168