In a class, the average age of 28 boys is 13 years. Two boys whose ages are ‘x’ years and 21 years leave the class. If the new average age of the class is 13 years, then what is the value of ‘x’?
Show answer & explanation
Correct answer: B
Explanation
Given:
Average age of 28 boys = 13 years
Two boys (x years old and 21 years old) leave.
New average age = 13 years
By the formula:
Total age = Average × Number
Initial total age = 28 × 13 = 364
New number = 26
New total age = 26 × 13 = 338
Removed age = 364 − 338 = 26
x + 21 = 26
x = 5