Question

The average age of 80 boys in a class is 15 years. The average age of a group of 15 boys in the class is 16 years and the average age of another 25 boys in the class is 14 years. What is the average age of the remaining boys in the class?

Options

• 15.25 years

• 14 years

• 14.75 years

• Cannot be determined

Answer 1

15.25 years

Explanation:

Let the required average age be x years.

Then 80 × 15 = 15 × 16 + 25 × 14 + 40 × x

⇒ 40x = 1200 – 240 – 350 = 610

∴ x = `610/40` = 15.25 years