PSLE
On Saturday, the number of adults to boys to girls visiting a bird park was 7 : 10 : 12. On Sunday, the number of adults visiting the bird park remained the same. However, the number of boys increased by 20% and the number of girls decreased by 25%.

1. What was the ratio of the number of adults to boys to girls visiting the bird park on Sunday?
2. On Saturday, 704 boys and girls visited the bird park. What was the total number of visitors at the bird park on Sunday?

	Adults	Boys	Girls
Before	7 u	10 u	12 u
Change		+ 2 u	- 3 u
After	7 u	12 u	9 u

(a)
Increase in the number of boys
= 20% x 10 u
= ²⁰₁₀₀ x 10 u
= 2 u

Decrease in the number of girls
= 25% x 12 u
= ²⁵₁₀₀ x 12 u
= 3 u

Number of boys on Sunday
= 10 u + 2 u
= 12 u

Number of girls on Sunday
= 12 u - 3 u
= 9 u

On Sunday
Adults : Boys : Girls
7 : 12 : 9

(b)
Number of boys and girls on Saturday
= 10 u + 12 u
= 22 u

22 u = 704

1 u = 704 ÷ 22 = 32

Total number of visitors on Sunday
= 7 u + 12 u + 9 u
= 28 u
= 28 x 32
= 896

Answer(s): (a) 7 : 12 : 9; (b) 896