PSLE
On Wednesday, the number of adults to boys to girls visiting a fun fair was 5 : 12 : 5. On Thursday, the number of adults visiting the fun fair remained the same. However, the number of boys decreased by 25% and the number of girls increased by 40%.

1. What was the ratio of the number of children to adults visiting the fun fair on Thursday?
2. On Wednesday, 731 boys and girls visited the fun fair. What was the total number of child visitors at the fun fair on Thursday?

	Adults	Boys	Girls
Before	5 u	12 u	5 u
Change		- 3 u	+ 2 u
After	5 u	9 u	7 u

(a)
Increase in the number of boys
= 25% x 12 u
= ²⁵₁₀₀ x 12 u
= 3 u

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

Number of boys on Thursday
= 12 u - 3 u
= 9 u

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

Number of children on Thursday
= 9 u + 7 u
= 16 u

On Thursday
Children : Adults
16 : 5

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

17 u = 731

1 u = 731 ÷ 17 = 43

Total number of child visitors on Thursday
= 16 u
= 16 x 43
= 688

Answer(s): (a) 16 : 5; (b) 688