The average age of a class of 65 boys is 14 years. The average age of 20 of them is 14 years, and the average age of another 15 boys is 12 years. What will be the average age (in years) of the remaining boys?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e 15.
Total number of boys = 65
Average age of all = 14
So, total age of all = 65 × 14 = 910
20 boys → average = 14 → total age = 20 × 14 = 280
15 boys → average = 12 → total age = 15 × 12 = 180
Remaining boys = 65 – 20 – 15 = 30
Their total age = 910 – (280 + 180) = 910 – 460 = 450
Average age of remaining boys = 450 ÷ 30 = 15 years