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 3 : 7. There are 5 times as many students in Group B as in Group A. There are 24 more boys in Group B than Group A. What is the total number of girls?
Group A |
Group B |
4 u |
10x2 = 20 u |
Boys |
Girls |
Boys |
Girls |
3 u |
1 u |
3x2 = 6 u |
7x2 = 14 u
|
Total number of students in Group A
= 3 u + 1 u
= 4 u
Total number of students in Group B
= 5 x 4 u
= 20 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 20 and 10 is 20.
Number of more boys in Group B than Group A
= 6 u - 3 u
= 3 u
3 u = 24
1 u = 24 ÷ 3 = 8
Total number of girls
= 1 u + 14 u
= 15 u
= 15 x 8
= 120
Answer(s): 120