PSLE
On Saturday, the number of adults to boys to girls visiting a zoo was 5 : 12 : 5. On Sunday, the number of adults visiting the zoo remained the same. However, the number of boys decreased by 50% and the number of girls increased by 40%.

1. What was the ratio of the number of children to adults visiting the zoo on Sunday?
2. On Saturday, 697 boys and girls visited the zoo. What was the total number of child visitors at the zoo on Sunday?

	Adults	Boys	Girls
Before	5 u	12 u	5 u
Change		- 6 u	+ 2 u
After	5 u	6 u	7 u

(a)
Increase in the number of boys
= 50% x 12 u
= ⁵⁰₁₀₀ x 12 u
= 6 u

Decrease in the number of girls
= 40% x 5 u
= ⁴⁰₁₀₀ x 5 u
= 2 u

Number of boys on Sunday
= 12 u - 6 u
= 6 u

Number of girls on Sunday
= 5 u + 2 u
= 7 u

Number of children on Sunday
= 6 u + 7 u
= 13 u

On Sunday
Children : Adults
13 : 5

(b)
Number of boys and girls on Saturday
= 12 u + 5 u
= 17 u

17 u = 697

1 u = 697 ÷ 17 = 41

Total number of child visitors on Sunday
= 13 u
= 13 x 41
= 533

Answer(s): (a) 13 : 5; (b) 533