PSLE
On Friday, the number of adults to boys to girls visiting a bird park was 1 : 10 : 4. On Saturday, the number of adults visiting the bird park remained the same. However, the number of boys increased by 30% and the number of girls decreased by 50%.

1. What was the ratio of the number of adults to boys to girls visiting the bird park on Saturday?
2. On Friday, 630 boys and girls visited the bird park. What was the total number of visitors at the bird park on Saturday?

	Adults	Boys	Girls
Before	1 u	10 u	4 u
Change		+ 3 u	- 2 u
After	1 u	13 u	2 u

(a)
Increase in the number of boys
= 30% x 10 u
= ³⁰₁₀₀ x 10 u
= 3 u

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

Number of boys on Saturday
= 10 u + 3 u
= 13 u

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

On Saturday
Adults : Boys : Girls
1 : 13 : 2

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

14 u = 630

1 u = 630 ÷ 14 = 45

Total number of visitors on Saturday
= 1 u + 13 u + 2 u
= 16 u
= 16 x 45
= 720

Answer(s): (a) 1 : 13 : 2; (b) 720