In a school, the ratio of adults to the number of children is 3 : 4.
The ratio of the number of boys to the number of girls is 5 : 4.
There are 100 less girls than boys.
How many people are there in the school?
Adults |
Children |
3 x 9 |
4 x 9 |
|
Boys |
Girls |
|
5 x 4 |
4 x 4 |
27 u |
20 u |
16 u |
The number of children is the combined repeated identity.
Make the number of children the same using the LCM of 4 and 9.
LCM of 4 and 9 = 36
Number of less girls than boys
= 20 u - 16 u
= 4 u
4 u = 100
1 u = 100 ÷ 4 = 25
Number of people
= 27 u + 20 u + 16 u
= 63 u
= 63 x 25
= 1575
Answer(s): 1575