PSLE The pupils at a school choir are divided in Group A and Group B. The ratio of the number of girls to boys in Group A is 2 : 1. The ratio of the number of girls to boys in Group B is 3 : 2. There are 5 times as many pupils in Group B as in Group A. There are 35 more girls in Group B than Group A. What is the total number of pupils?
Group A |
Group B |
3 u |
5x3 = 15 u |
Girls |
Boys |
Girls |
Boys |
2 u |
1 u |
3x3 = 9 u |
2x3 = 6 u
|
Total number of pupils in Group A
= 2 u + 1 u
= 3 u
Total number of pupils in Group B
= 5 x 3 u
= 15 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 15 and 5 is 15.
Number of more girls in Group B than Group A
= 9 u - 2 u
= 7 u
7 u = 35
1 u = 35 ÷ 7 = 5
Total number of pupils
= 2 u + 1 u + 9 u + 6 u
= 18 u
= 18 x 5
= 90
Answer(s): 90