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 4 : 1. The ratio of the number of boys to girls in Group B is 7 : 3. There are 4 times as many students in Group B as in Group A. There are 20 more boys in Group B than Group A. What is the total number of girls?
Group A |
Group B |
5 u |
10x2 = 20 u |
Boys |
Girls |
Boys |
Girls |
4 u |
1 u |
7x2 = 14 u |
3x2 = 6 u
|
Total number of students in Group A
= 4 u + 1 u
= 5 u
Total number of students in Group B
= 4 x 5 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
= 14 u - 4 u
= 10 u
10 u = 20
1 u = 20 ÷ 10 = 2
Total number of girls
= 1 u + 6 u
= 7 u
= 7 x 2
= 14
Answer(s): 14