PSLE
The pupils at a school choir are divided in Group A and Group B. The ratio of the number of boys to girls in Group A is 6 : 1. The ratio of the number of boys to girls in Group B is 11 : 3. There are 4 times as many pupils in Group B as in Group A. There are 112 more boys in Group B than Group A. What is the total number of pupils?

Group A		Group B
7 u		14x2 = 28 u
Boys	Girls	Boys	Girls
6 u	1 u	11x2 = 22 u	3x2 = 6 u

Total number of pupils in Group A
= 6 u + 1 u
= 7 u

Total number of pupils in Group B
= 4 x 7 u
= 28 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 28 and 14 is 28.

Number of more boys in Group B than Group A
= 22 u - 6 u
= 16 u

16 u = 112

1 u = 112 ÷ 16 = 7

Total number of pupils
= 6 u + 1 u + 22 u + 6 u
= 35 u
= 35 x 7
= 245

Answer(s): 245