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 3 : 1.
There are 90 more boys than girls.
How many people are there in the school?
Adults |
Children |
2 x 4 |
9 x 4 |
|
Boys |
Girls |
|
3 x 9 |
1 x 9 |
8 u |
27 u |
9 u |
The number of children is the combined repeated identity.
Make the number of children the same using the LCM of 9 and 4.
LCM of 9 and 4 = 36
Number of more boys than girls
= 27 u - 9 u
= 18 u
18 u = 90
1 u = 90 ÷ 18 = 5
Number of people
= 8 u + 27 u + 9 u
= 44 u
= 44 x 5
= 220
Answer(s): 220