In a school, the ratio of adults to the number of children is 9 : 5.
The ratio of the number of boys to the number of girls is 4 : 1.
There are 15 less girls than boys.
How many people are there in the school?
Adults |
Children |
9 x 1 |
5 x 1 |
|
Boys |
Girls |
|
4 x 1 |
1 x 1 |
9 u |
4 u |
1 u |
The number of children is the combined repeated identity.
Make the number of children the same using the LCM of 5 and 5.
LCM of 5 and 5 = 5
Number of less girls than boys
= 4 u - 1 u
= 3 u
3 u = 15
1 u = 15 ÷ 3 = 5
Number of people
= 9 u + 4 u + 1 u
= 14 u
= 14 x 5
= 70
Answer(s): 70