the ratio of girls to boys in a school is 3 to 1. If there is a total of 400 students, how many are boys? The answer has to be a whole number.
We can set up a proportion to solve this problem:
Let x represent the number of girls and y represent the number of boys.
From the given ratio, we know that $\frac{x}{y} = \frac{3}{1}$. Rearranging this ratio, we get $x = 3y$.
We also know that the total number of students is 400, so we have the equation $x + y = 400$.
Substituting the value of x from the first equation into the second equation, we get $3y + y = 400$.
Combining like terms, we have $4y = 400$.
Dividing both sides of the equation by 4, we find $y = 100$.
Therefore, there are 100 boys in the school.