PSLE
On Thursday, the number of adults to girls to boys visiting a zoo was 1 : 10 : 10. On Friday, the number of adults visiting the zoo remained the same. However, the number of girls decreased by 30% and the number of boys increased by 10%.

1. What was the ratio of the number of children to adults visiting the zoo on Friday?
2. On Thursday, 700 girls and boys visited the zoo. What was the total number of child visitors at the zoo on Friday?

	Adults	Girls	Boys
Before	1 u	10 u	10 u
Change		- 3 u	+ 1 u
After	1 u	7 u	11 u

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

Decrease in the number of boys
= 10% x 10 u
= ¹⁰₁₀₀ x 10 u
= 1 u

Number of girls on Friday
= 10 u - 3 u
= 7 u

Number of boys on Friday
= 10 u + 1 u
= 11 u

Number of children on Friday
= 7 u + 11 u
= 18 u

On Friday
Children : Adults
18 : 1

(b)
Number of girls and boys on Thursday
= 10 u + 10 u
= 20 u

20 u = 700

1 u = 700 ÷ 20 = 35

Total number of child visitors on Friday
= 18 u
= 18 x 35
= 630

Answer(s): (a) 18 : 1; (b) 630