PSLE
The pupils at a camp are divided in Group A and Group B. The ratio of the number of girls to boys in Group A is 3 : 1. The ratio of the number of girls to boys in Group B is 2 : 1. There are 3 times as many pupils in Group B as in Group A. There are 65 more girls in Group B than Group A. What is the total number of pupils?

Group A		Group B
4 u		3x4 = 12 u
Girls	Boys	Girls	Boys
3 u	1 u	2x4 = 8 u	1x4 = 4 u

Total number of pupils in Group A
= 3 u + 1 u
= 4 u

Total number of pupils in Group B
= 3 x 4 u
= 12 u

The total number of pupils in Group B is repeated.
Use LCM to make the total number of pupils in Group B the same.
LCM of 12 and 3 is 12.

Number of more girls in Group B than Group A
= 8 u - 3 u
= 5 u

5 u = 65

1 u = 65 ÷ 5 = 13

Total number of pupils
= 3 u + 1 u + 8 u + 4 u
= 16 u
= 16 x 13
= 208

Answer(s): 208