In a school, the ratio of adults to the number of children is 9 : 2.
The ratio of the number of boys to the number of girls is 3 : 2.
There are 18 less girls than boys.
How many people are there in the school?
Adults |
Children |
9 x 5 |
2 x 5 |
|
Boys |
Girls |
|
3 x 2 |
2 x 2 |
45 u |
6 u |
4 u |
The number of children is the combined repeated identity.
Make the number of children the same using the LCM of 2 and 5.
LCM of 2 and 5 = 10
Number of less girls than boys
= 6 u - 4 u
= 2 u
2 u = 18
1 u = 18 ÷ 2 = 9
Number of people
= 45 u + 6 u + 4 u
= 55 u
= 55 x 9
= 495
Answer(s): 495