Question

The percent of boys in a class was 40%. How many students are there in the class?

Please help with a good and clear explanation!

Answer 1

To answer the question it necessary to know either the number of boys or the number of girls in the class.

Answer 2

A multiple of `5`

Explanation:

Percent means "per hundred", expressing a proportion.

The proportion of boys in the class is:

`40/100 = (2*color(red)(cancel(color(black)(20))))/(5*color(red)(cancel(color(black)(20)))) = 2/5`

In other words, for every `5` students in the class, `2` are boys and `3` are girls.

In order that the figure `40%` be exact, the number of students must be a multiple of `5`.

Then the number of boys will be the corresponding multiple of `2` and the number of girls the corresponding multiple of `3`.

That is about as much as we can deduce from the question as given.