PSLE
The contestants at a contest are divided in Group A and Group B. The ratio of the number of girls to boys in Group A is 3 : 2. The ratio of the number of girls to boys in Group B is 3 : 7. There are 4 times as many contestants in Group B as in Group A. There are 33 more girls in Group B than Group A. What is the total number of contestants?

Group A		Group B
5 u		10x2 = 20 u
Girls	Boys	Girls	Boys
3 u	2 u	3x2 = 6 u	7x2 = 14 u

Total number of contestants in Group A
= 3 u + 2 u
= 5 u

Total number of contestants in Group B
= 4 x 5 u
= 20 u

The total number of contestants in Group B is repeated.
Use LCM to make the total number of contestants in Group B the same.
LCM of 20 and 10 is 20.

Number of more girls in Group B than Group A
= 6 u - 3 u
= 3 u

3 u = 33

1 u = 33 ÷ 3 = 11

Total number of contestants
= 3 u + 2 u + 6 u + 14 u
= 25 u
= 25 x 11
= 275

Answer(s): 275