In a school, the number of students who are above 15 years is 20% and the rest are below 15 years. The number of girls who are above 15 years of age is 80% of the students who are above 15 years of age. The number of boys who are below 15 years of age is 30% of the students who are below 15 years of age. If the total number of girls who are below 15 years of age is 1120, then, find the number of boys who are above 15 years of age in the school?

In a school, the number of students who are above 15 years is 20% and the rest are below 15 years. The number of girls who are above 15 years of age is 80% of the students who are above 15 years of age. The number of boys who are below 15 years of age is 30% of the students who are below 15 years of age. If the total number of girls who are below 15 years of age is 1120, then, find the number of boys who are above 15 years of age in the school? Correct Answer 80

Let the total number of students in school is 100x.

The number of students who are above 15 years of age = 20x

The number of students who are below 15 years of age = 80x

According to question,

The number of girls who are above 15 years of age = 80% of 20x = 16x

The number of boys who are below 15 years of age = 30% of 80x = 24x

So, the number of girls who are below 15 years of age = (80x - 24x) = 56x

Given, 56x = 280

⇒ x = 1120 / 56

⇒ x = 20