Question

The average age of 15 students is 16 years. If teacher’s age is included the average increases by 1. Find teacher’s age. (a) 30 years (b) 32 years (c) 58 years (d) 60 years

Answer 1

Age of teacher = 32 years

Therefore, the correct answer is (b)

Explanation:

We know that average is given by

Average age = Sum of ages /no. of students

We are given that the average age of 15 students is 16 years.

16 = Sum of ages/15

Sum of ages = 16×15

Sum of ages = 240

We are given that If teacher’s age is included the average increases by 1.

16 + 1 = New sum of ages/15 + 1

17 = New sum of ages/16

New sum of ages = 17×16

New sum of ages = 272

So the age of the teacher is found by

Age of teacher = New sum of ages - Sum of ages

Age of teacher = 272 - 240

Age of teacher = 32 years

Therefore, the correct answer is (b)

Answer 2

Age of teacher = 32 years

Explanation:

Average age of 15 students = 16 years

Sum of age of 15 students = 16 * 15 = 240 years

Average of age 15 students and a teacher = 17 years

Sum of age 15 students and a teacher = 17 * 16 = 272 years

Age of teacher = 272 - 240 = 32 years