PSLE The pupils at a school choir are divided in Team A and Team B. The ratio of the number of girls to boys in Team A is 3 : 1. The ratio of the number of girls to boys in Team B is 9 : 1. There are 5 times as many pupils in Team B as in Team A. There are 60 more girls in Team B than Team A. What is the total number of boys?
Team A |
Team B |
4 u |
10x2 = 20 u |
Girls |
Boys |
Girls |
Boys |
3 u |
1 u |
9x2 = 18 u |
1x2 = 2 u
|
Total number of pupils in Team A
= 3 u + 1 u
= 4 u
Total number of pupils in Team B
= 5 x 4 u
= 20 u
The total number of pupils in Team B is repeated.
Use LCM to make the total number of pupils in Team B the same.
LCM of 20 and 10 is 20.
Number of more girls in Team B than Team A
= 18 u - 3 u
= 15 u
15 u = 60
1 u = 60 ÷ 15 = 4
Total number of boys
= 1 u + 2 u
= 3 u
= 3 x 4
= 12
Answer(s): 12