The average age of a group of 20 boys is 25 years. A boy aged 15 years leaves the group. A new boy joins the group and the average age of the group increases by 2 years. What is the age of the new boy?

Correct option is D

Formula Used:
Sum of ages = Average age × Number of boys

Solution:
Let the age of the new boy be x.
Initial total age of the group = 25 × 20 = 500 years
After the 15-year-old boy leaves, the total age = 500 - 15 = 485 years
New total age of the group after a new boy joins = 27 × 20 = 540 years
Therefore, the age of the new boy (x) = 540 - 485 = 55 years