PSLE
The students at a sports meet are divided in Group A and Group B. The ratio of the number of girls to boys in Group A is 6 : 1. The ratio of the number of girls to boys in Group B is 5 : 9. There are 4 times as many students in Group B as in Group A. There are 8 more girls in Group B than Group A. What is the total number of students?

Group A		Group B
7 u		14x2 = 28 u
Girls	Boys	Girls	Boys
6 u	1 u	5x2 = 10 u	9x2 = 18 u

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

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

Number of more girls in Group B than Group A
= 10 u - 6 u
= 4 u

4 u = 8

1 u = 8 ÷ 4 = 2

Total number of students
= 6 u + 1 u + 10 u + 18 u
= 35 u
= 35 x 2
= 70

Answer(s): 70