Question

The ratio of girls to boys in a certain grade is 9;8. If there are 72 girls in the grade, how many boys are there?

Answer 1

`Boys = 81`

Explanation:

Given

`Boys : Girls = 9 : 8`

`Girls = 72`

Required

Find the number of boys

Substitute 72 for girls in
`Boys : Girls = 9 : 8`

`Boys : 72 = 9 : 8`

Convert ratio to fraction

`(Boys)/(72) = (9)/(8)`

Multiply both sides by 72

`72 * (Boys)/(72) = (9)/(8) * 72`

`Boys = (9)/(8) * 72`

`Boys = 9*9`

`Boys = 81`