PSLE
On Tuesday, the number of adults to girls to boys visiting a safari park was 1 : 5 : 5. On Wednesday, the number of adults visiting the safari park remained the same. However, the number of girls increased by 20% and the number of boys decreased by 40%.

1. What was the ratio of the number of adults to girls to boys visiting the safari park on Wednesday?
2. On Tuesday, 250 girls and boys visited the safari park. What was the total number of visitors at the safari park on Wednesday?

	Adults	Girls	Boys
Before	1 u	5 u	5 u
Change		+ 1 u	- 2 u
After	1 u	6 u	3 u

(a)
Increase in the number of girls
= 20% x 5 u
= ²⁰₁₀₀ x 5 u
= 1 u

Decrease in the number of boys
= 40% x 5 u
= ⁴⁰₁₀₀ x 5 u
= 2 u

Number of girls on Wednesday
= 5 u + 1 u
= 6 u

Number of boys on Wednesday
= 5 u - 2 u
= 3 u

On Wednesday
Adults : Girls : Boys
1 : 6 : 3

(b)
Number of girls and boys on Tuesday
= 5 u + 5 u
= 10 u

10 u = 250

1 u = 250 ÷ 10 = 25

Total number of visitors on Wednesday
= 1 u + 6 u + 3 u
= 10 u
= 10 x 25
= 250

Answer(s): (a) 1 : 6 : 3; (b) 250