The average age of 52 students of a class is 12 years. If the age of the teacher is also included, the average age of the whole group becomes 13 years. The age (in years) of the teacher is:
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 65 .
Number of students = 52
Average age of students = 12 years
Total age of students = 52 × 12 = 624
Including teacher, total people = 52 + 1 = 53
New average = 13 years
Total age of group = 53 × 13 = 689
Age of teacher = 689 − 624 = 65