PSLE
On Friday, the number of adults to girls to boys visiting a bird park was 1 : 4 : 12. On Saturday, 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 25%.

1. What was the ratio of the number of children to adults visiting the bird park on Saturday?
2. On Friday, 336 girls and boys visited the bird park. What was the total number of child visitors at the bird park on Saturday?

	Adults	Girls	Boys
Before	1 u	4 u	12 u
Change		- 2 u	+ 3 u
After	1 u	2 u	15 u

(a)
Increase in the number of girls
= 50% x 4 u
= ⁵⁰₁₀₀ x 4 u
= 2 u

Decrease in the number of boys
= 25% x 12 u
= ²⁵₁₀₀ x 12 u
= 3 u

Number of girls on Saturday
= 4 u - 2 u
= 2 u

Number of boys on Saturday
= 12 u + 3 u
= 15 u

Number of children on Saturday
= 2 u + 15 u
= 17 u

On Saturday
Children : Adults
17 : 1

(b)
Number of girls and boys on Friday
= 4 u + 12 u
= 16 u

16 u = 336

1 u = 336 ÷ 16 = 21

Total number of child visitors on Saturday
= 17 u
= 17 x 21
= 357

Answer(s): (a) 17 : 1; (b) 357