Question

In a class, the average age of 40 students is 12 years when teacher’s age is included to it, the average increases by 1. The age of teacher is :

• A. 53 years
• B. 51 years
• C. 48 years
• D. 68 years

Answer 1

Answer:

A. 53 years

Solution: Given: The average age of 40 students is 12 years When the teacher’s age is included to it, the average increases by 1 Concept Used: Sum of all quantity = Average × Number of quantities Calculation: The average age of 40 students is 12 years Sum of the age of 40 students is 40 × 12 = 480 years When the teacher’s age is included to it, the average increases by 1 Then average age (12 + 1) = 13 years and total number of man is (40 + 1) = 41 Then total age = (41 × 13) years ⇒ 533 years Age of the teacher is (533 – 480) = 53 years Alternative Method: Average age increased by 1 years Total age increase of 40 students is 40 years New average age = (12 + 1) = 13 year ∴ age of the teacher = (40 + 13) = 53 years