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 7 : 3. The ratio of the number of girls to boys in Group B is 4 : 1. There are 2 times as many students in Group B as in Group A. There are 99 more girls in Group B than Group A. What is the total number of boys?
Group A |
Group B |
10 u |
5x4 = 20 u |
Girls |
Boys |
Girls |
Boys |
7 u |
3 u |
4x4 = 16 u |
1x4 = 4 u
|
Total number of students in Group A
= 7 u + 3 u
= 10 u
Total number of students in Group B
= 2 x 10 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 5 is 20.
Number of more girls in Group B than Group A
= 16 u - 7 u
= 9 u
9 u = 99
1 u = 99 ÷ 9 = 11
Total number of boys
= 3 u + 4 u
= 7 u
= 7 x 11
= 77
Answer(s): 77