PSLE The pupils at a camp are divided in Group A and Group B. The ratio of the number of boys to girls in Group A is 6 : 1. The ratio of the number of boys to girls in Group B is 13 : 1. There are 4 times as many pupils in Group B as in Group A. There are 100 less boys in Group A than Group B. What is the total number of pupils in Group A?
Group A |
Group B |
7 u |
14x2 = 28 u |
Boys |
Girls |
Boys |
Girls |
6 u |
1 u |
13x2 = 26 u |
1x2 = 2 u
|
Total number of pupils in Group A
= 6 u + 1 u
= 7 u
Total number of pupils in Group B
= 4 x 7 u
= 28 u
The total number of pupils in Group B is repeated.
Use LCM to make the total number of pupils in Group B the same.
LCM of 28 and 14 is 28.
Number of less boys in Group A than Group B
= 26 u - 6 u
= 20 u
20 u = 100
1 u = 100 ÷ 20 = 5
Total number of pupils in Group A
= 6 u + 1 u
= 7 u
= 7 x 5
= 35
Answer(s): 35