PSLE
On Monday, the number of adults to girls to boys visiting a safari park was 7 : 8 : 4. On Tuesday, the number of adults visiting the safari park remained the same. However, the number of girls increased by 25% and the number of boys decreased by 25%.

1. What was the ratio of the number of adults to girls to boys visiting the safari park on Tuesday?
2. On Monday, 492 girls and boys visited the safari park. What was the total number of visitors at the safari park on Tuesday?

	Adults	Girls	Boys
Before	7 u	8 u	4 u
Change		+ 2 u	- 1 u
After	7 u	10 u	3 u

(a)
Increase in the number of girls
= 25% x 8 u
= ²⁵₁₀₀ x 8 u
= 2 u

Decrease in the number of boys
= 25% x 4 u
= ²⁵₁₀₀ x 4 u
= 1 u

Number of girls on Tuesday
= 8 u + 2 u
= 10 u

Number of boys on Tuesday
= 4 u - 1 u
= 3 u

On Tuesday
Adults : Girls : Boys
7 : 10 : 3

(b)
Number of girls and boys on Monday
= 8 u + 4 u
= 12 u

12 u = 492

1 u = 492 ÷ 12 = 41

Total number of visitors on Tuesday
= 7 u + 10 u + 3 u
= 20 u
= 20 x 41
= 820

Answer(s): (a) 7 : 10 : 3; (b) 820