The average age of 40 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: C
Explanation
The correct answer is Option 3 i.e. 53.
Average age of 40 students = 12
Total age of 40 students = 40 × 12 = 480
New average with teacher = 13
Total people = 41
Total age = 41 × 13 = 533
Teacher’s age = 533 − 480 = 53 years