PSLE
On Wednesday, the number of adults to boys to girls visiting a zoo was 1 : 5 : 4. On Thursday, the number of adults visiting the zoo remained the same. However, the number of boys decreased by 40% and the number of girls increased by 50%.

1. What was the ratio of the number of children to adults visiting the zoo on Thursday?
2. On Wednesday, 333 boys and girls visited the zoo. What was the total number of child visitors at the zoo on Thursday?

	Adults	Boys	Girls
Before	1 u	5 u	4 u
Change		- 2 u	+ 2 u
After	1 u	3 u	6 u

(a)
Increase in the number of boys
= 40% x 5 u
= ⁴⁰₁₀₀ x 5 u
= 2 u

Decrease in the number of girls
= 50% x 4 u
= ⁵⁰₁₀₀ x 4 u
= 2 u

Number of boys on Thursday
= 5 u - 2 u
= 3 u

Number of girls on Thursday
= 4 u + 2 u
= 6 u

Number of children on Thursday
= 3 u + 6 u
= 9 u

On Thursday
Children : Adults
9 : 1

(b)
Number of boys and girls on Wednesday
= 5 u + 4 u
= 9 u

9 u = 333

1 u = 333 ÷ 9 = 37

Total number of child visitors on Thursday
= 9 u
= 9 x 37
= 333

Answer(s): (a) 9 : 1; (b) 333