PSLE
On Thursday, the number of adults to girls to boys visiting a bird park was 3 : 2 : 10. On Friday, the number of adults visiting the bird park remained the same. However, the number of girls decreased by 50% and the number of boys increased by 40%.

1. What was the ratio of the number of children to adults visiting the bird park on Friday?
2. On Thursday, 564 girls and boys visited the bird park. What was the total number of child visitors at the bird park on Friday?

	Adults	Girls	Boys
Before	3 u	2 u	10 u
Change		- 1 u	+ 4 u
After	3 u	1 u	14 u

(a)
Increase in the number of girls
= 50% x 2 u
= ⁵⁰₁₀₀ x 2 u
= 1 u

Decrease in the number of boys
= 40% x 10 u
= ⁴⁰₁₀₀ x 10 u
= 4 u

Number of girls on Friday
= 2 u - 1 u
= 1 u

Number of boys on Friday
= 10 u + 4 u
= 14 u

Number of children on Friday
= 1 u + 14 u
= 15 u

On Friday
Children : Adults
15 : 3

(b)
Number of girls and boys on Thursday
= 2 u + 10 u
= 12 u

12 u = 564

1 u = 564 ÷ 12 = 47

Total number of child visitors on Friday
= 15 u
= 15 x 47
= 705

Answer(s): (a) 15 : 3; (b) 705