PSLE
On Tuesday, the number of adults to girls to boys visiting a park was 7 : 4 : 8. On Wednesday, the number of adults visiting the park remained the same. However, the number of girls increased by 25% and the number of boys decreased by 50%.

1. What was the ratio of the number of adults to girls to boys visiting the park on Wednesday?
2. On Tuesday, 432 girls and boys visited the park. What was the total number of visitors at the park on Wednesday?

	Adults	Girls	Boys
Before	7 u	4 u	8 u
Change		+ 1 u	- 4 u
After	7 u	5 u	4 u

(a)
Increase in the number of girls
= 25% x 4 u
= ²⁵₁₀₀ x 4 u
= 1 u

Decrease in the number of boys
= 50% x 8 u
= ⁵⁰₁₀₀ x 8 u
= 4 u

Number of girls on Wednesday
= 4 u + 1 u
= 5 u

Number of boys on Wednesday
= 8 u - 4 u
= 4 u

On Wednesday
Adults : Girls : Boys
7 : 5 : 4

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

12 u = 432

1 u = 432 ÷ 12 = 36

Total number of visitors on Wednesday
= 7 u + 5 u + 4 u
= 16 u
= 16 x 36
= 576

Answer(s): (a) 7 : 5 : 4; (b) 576