Question

3/4 of all the girls in a certain class have cell phones. 2/5 of all the boys in that class also have cell phones. The number of girls who have cell phones is equal to the number of boys who have cell phones. In lowest terms, what fraction of the whole class have cell phones?

Answer 1

Explanation:

Let total number of girls and boys be x and y respectively.

`\therefore \: (3)/(4) x = (2)/(5) y \\ \\ \therefore \: (x)/(y) = (2)/(5) * (4)/(3) \\ \\ \therefore \: (x)/(y) = (2 * 4)/(5 * 3) \\ \\ \therefore \: (x)/(y) = (8)/(15) \\ \\`

`\therefore \: (3)/(4) x = (2)/(5) y \\ \\ \therefore \: (x)/(y) = (2)/(5) * (4)/(3) \\ \\ \therefore \: (x)/(y) = (2 * 4)/(5 * 3) \\ \\ \therefore \: (x)/(y) = (8)/(15) \\ \\ \therefore \: \: (8)/(15) \: of \: the \: whole \: class \: have \: cell \: \\ phones.`