PSLE
On Monday, the number of adults to girls to boys visiting a zoo was 5 : 10 : 4. On Tuesday, the number of adults visiting the zoo remained the same. However, the number of girls decreased by 40% and the number of boys increased by 50%.

1. What was the ratio of the number of children to adults visiting the zoo on Tuesday?
2. On Monday, 602 girls and boys visited the zoo. What was the total number of child visitors at the zoo on Tuesday?

	Adults	Girls	Boys
Before	5 u	10 u	4 u
Change		- 4 u	+ 2 u
After	5 u	6 u	6 u

(a)
Increase in the number of girls
= 40% x 10 u
= ⁴⁰₁₀₀ x 10 u
= 4 u

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

Number of girls on Tuesday
= 10 u - 4 u
= 6 u

Number of boys on Tuesday
= 4 u + 2 u
= 6 u

Number of children on Tuesday
= 6 u + 6 u
= 12 u

On Tuesday
Children : Adults
12 : 5

(b)
Number of girls and boys on Monday
= 10 u + 4 u
= 14 u

14 u = 602

1 u = 602 ÷ 14 = 43

Total number of child visitors on Tuesday
= 12 u
= 12 x 43
= 516

Answer(s): (a) 12 : 5; (b) 516