In a school, the ratio of adults to the number of children is 2 : 1.
The ratio of the number of girls to the number of boys is 3 : 1.
There are 80 more girls than boys.
How many people are there in the school?
Adults |
Children |
2 x 4 |
1 x 4 |
|
Girls |
Boys |
|
3 x 1 |
1 x 1 |
8 u |
3 u |
1 u |
The number of children is the combined repeated identity.
Make the number of children the same using the LCM of 1 and 4.
LCM of 1 and 4 = 4
Number of more girls than boys
= 3 u - 1 u
= 2 u
2 u = 80
1 u = 80 ÷ 2 = 40
Number of people
= 8 u + 3 u + 1 u
= 12 u
= 12 x 40
= 480
Answer(s): 480