PSLE The contestants at a contest are divided in Group A and Group B. The ratio of the number of girls to boys in Group A is 7 : 5. The ratio of the number of girls to boys in Group B is 5 : 1. There are 2 times as many contestants in Group B as in Group A. There are 65 less girls in Group A than Group B. What is the total number of contestants in Group A?
Group A |
Group B |
12 u |
6x4 = 24 u |
Girls |
Boys |
Girls |
Boys |
7 u |
5 u |
5x4 = 20 u |
1x4 = 4 u
|
Total number of contestants in Group A
= 7 u + 5 u
= 12 u
Total number of contestants in Group B
= 2 x 12 u
= 24 u
The total number of contestants in Group B is repeated.
Use LCM to make the total number of contestants in Group B the same.
LCM of 24 and 6 is 24.
Number of less girls in Group A than Group B
= 20 u - 7 u
= 13 u
13 u = 65
1 u = 65 ÷ 13 = 5
Total number of contestants in Group A
= 7 u + 5 u
= 12 u
= 12 x 5
= 60
Answer(s): 60