PSLE
On Thursday, the number of adults to boys to girls visiting a museum was 1 : 2 : 12. On Friday, the number of adults visiting the museum remained the same. However, the number of boys decreased by 50% and the number of girls increased by 25%.

1. What was the ratio of the number of children to adults visiting the museum on Friday?
2. On Thursday, 490 boys and girls visited the museum. What was the total number of child visitors at the museum on Friday?

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

(a)
Increase in the number of boys
= 50% x 2 u
= ⁵⁰₁₀₀ x 2 u
= 1 u

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

Number of boys on Friday
= 2 u - 1 u
= 1 u

Number of girls on Friday
= 12 u + 3 u
= 15 u

Number of children on Friday
= 1 u + 15 u
= 16 u

On Friday
Children : Adults
16 : 1

(b)
Number of boys and girls on Thursday
= 2 u + 12 u
= 14 u

14 u = 490

1 u = 490 ÷ 14 = 35

Total number of child visitors on Friday
= 16 u
= 16 x 35
= 560

Answer(s): (a) 16 : 1; (b) 560