PSLE
The students at a sports meet are divided in Group A and Group B. The ratio of the number of boys to girls in Group A is 3 : 1. The ratio of the number of boys to girls in Group B is 2 : 1. There are 3 times as many students in Group B as in Group A. There are 40 more boys in Group B than Group A. What is the total number of students?

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

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

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

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

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

5 u = 40

1 u = 40 ÷ 5 = 8

Total number of students
= 3 u + 1 u + 8 u + 4 u
= 16 u
= 16 x 8
= 128

Answer(s): 128