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

1. What was the ratio of the number of adults to girls to boys visiting the museum on Friday?
2. On Thursday, 528 girls and boys visited the museum. What was the total number of visitors at the museum on Friday?

	Adults	Girls	Boys
Before	1 u	12 u	12 u
Change		+ 6 u	- 6 u
After	1 u	18 u	6 u

(a)
Increase in the number of girls
= 50% x 12 u
= ⁵⁰₁₀₀ x 12 u
= 6 u

Decrease in the number of boys
= 50% x 12 u
= ⁵⁰₁₀₀ x 12 u
= 6 u

Number of girls on Friday
= 12 u + 6 u
= 18 u

Number of boys on Friday
= 12 u - 6 u
= 6 u

On Friday
Adults : Girls : Boys
1 : 18 : 6

(b)
Number of girls and boys on Thursday
= 12 u + 12 u
= 24 u

24 u = 528

1 u = 528 ÷ 24 = 22

Total number of visitors on Friday
= 1 u + 18 u + 6 u
= 25 u
= 25 x 22
= 550

Answer(s): (a) 1 : 18 : 6; (b) 550