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?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 55 years .
Total age = Average age × Number of boys = 25 × 20 = 500 years
The total age after the boy aged 15 years.
New total age = 500 - 15 = 485 years
The total age after the new boy joins.
New average age = 25 + 2 = 27 years
The new total age of the group:
New total age = 27 × 20 = 540 years.
The age of the new boy.
Age of new boy = 540 - 485 = 55 years
The age of the new boy is 55 years.