In a school, the ratio of adults to the number of children is 2 : 9.
The ratio of the number of boys to the number of girls is 6 : 5.
There are 81 more boys than girls.
How many people are there in the school?
Adults |
Children |
2 x 11 |
9 x 11 |
|
Boys |
Girls |
|
6 x 9 |
5 x 9 |
22 u |
54 u |
45 u |
The number of children is the combined repeated identity.
Make the number of children the same using the LCM of 9 and 11.
LCM of 9 and 11 = 99
Number of more boys than girls
= 54 u - 45 u
= 9 u
9 u = 81
1 u = 81 ÷ 9 = 9
Number of people
= 22 u + 54 u + 45 u
= 121 u
= 121 x 9
= 1089
Answer(s): 1089