If 40% of a school consists of boys, 40 % of the students have blonde hair, and three times as many girls as boys have blond hair, what percentage of the school are blonde haired boys?

10% of the school are blonde haired boys.

Step-by-step explanation:

Let x be the total number of students,

Number of students who have blonde hair = 40% of the total students

= 40% of x

= 0.4x

Also, the ratio of three times as many girls as boys have blond hair,

So, the ratio of blond hair boys and blond hair girls = 1 : 3

Let the number of boys who have blonde hair = y

And, the number of girls who have blonde hair = 3y

So, y + 3y = 0.4x

4y = 0.4x ⇒ y = 0.1x

Thus, the number of boys who have blonde hair = 0.1x

Hence, the percentage of the school are blonde haired boys

=