Question

The average age of 40 students in a group is 16 years. When teacher's age is included to it, the average increases by one. Find out the teacher's age in years.

• A. 50
• B. 47
• C. 57
• D. 49
• E. 54

Answer 1

The correct option is C

57

Average age of 40 students in a group is 16

$\Rightarrow$ Sum of the ages of 40 students =40 $\times$ 16

When teacher's age is included to it, the average increases by one

$\Rightarrow$ Average = 17

$\Rightarrow$ Sum of the ages of 40 students and the teacher =41$\times$17

Hence teacher's age =(40 $\times$ 16) - (41 $\times$ 17) = 57