PSLE
On Saturday, the number of adults to girls to boys visiting a bird park was 5 : 6 : 10. On Sunday, the number of adults visiting the bird park remained the same. However, the number of girls increased by 50% and the number of boys decreased by 50%.

1. What was the ratio of the number of adults to girls to boys visiting the bird park on Sunday?
2. On Saturday, 672 girls and boys visited the bird park. What was the total number of visitors at the bird park on Sunday?

	Adults	Girls	Boys
Before	5 u	6 u	10 u
Change		+ 3 u	- 5 u
After	5 u	9 u	5 u

(a)
Increase in the number of girls
= 50% x 6 u
= ⁵⁰₁₀₀ x 6 u
= 3 u

Decrease in the number of boys
= 50% x 10 u
= ⁵⁰₁₀₀ x 10 u
= 5 u

Number of girls on Sunday
= 6 u + 3 u
= 9 u

Number of boys on Sunday
= 10 u - 5 u
= 5 u

On Sunday
Adults : Girls : Boys
5 : 9 : 5

(b)
Number of girls and boys on Saturday
= 6 u + 10 u
= 16 u

16 u = 672

1 u = 672 ÷ 16 = 42

Total number of visitors on Sunday
= 5 u + 9 u + 5 u
= 19 u
= 19 x 42
= 798

Answer(s): (a) 5 : 9 : 5; (b) 798