Correct option is D
Given:
Number of students = 52
Average age of students = 12 years
Average age of the whole group (students + teacher) = 13 years
Formula Used:
Total age = Average age × Number of individuals
Solution:
Total age of 52 students = 12 × 52 = 624
Total number of individuals in the group = 52 + 1 = 53
Total age of the group = 13 × 53 = 689
Age of the teacher = 689 - 624 = 65