The average age of 22 students of a class is 47 years. If the age of the teacher is also included, the average age of the whole group becomes 48 years. The age (in years) of the teacher is:
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1 i.e. 70.
Let teacher's age = x
(22 × 47 + x) / 23 = 48
(1034 + x) = 48 × 23 = 1104
x = 1104 – 1034 = 70