PSLE
On Wednesday, the number of adults to girls to boys visiting a bird park was 3 : 10 : 8. On Thursday, the number of adults visiting the bird park remained the same. However, the number of girls increased by 30% and the number of boys decreased by 25%.

1. What was the ratio of the number of adults to girls to boys visiting the bird park on Thursday?
2. On Wednesday, 396 girls and boys visited the bird park. What was the total number of visitors at the bird park on Thursday?

	Adults	Girls	Boys
Before	3 u	10 u	8 u
Change		+ 3 u	- 2 u
After	3 u	13 u	6 u

(a)
Increase in the number of girls
= 30% x 10 u
= ³⁰₁₀₀ x 10 u
= 3 u

Decrease in the number of boys
= 25% x 8 u
= ²⁵₁₀₀ x 8 u
= 2 u

Number of girls on Thursday
= 10 u + 3 u
= 13 u

Number of boys on Thursday
= 8 u - 2 u
= 6 u

On Thursday
Adults : Girls : Boys
3 : 13 : 6

(b)
Number of girls and boys on Wednesday
= 10 u + 8 u
= 18 u

18 u = 396

1 u = 396 ÷ 18 = 22

Total number of visitors on Thursday
= 3 u + 13 u + 6 u
= 22 u
= 22 x 22
= 484

Answer(s): (a) 3 : 13 : 6; (b) 484