###
**The average age of a class of 39 students is 15 years. If the age of the teacher is included, then the average increases by 3 months. Find the age of the teacher.**

A. 30 years
B. 25 years
C. 35 years
D. 40 years
**Answer: Option B**

## Show Answer

Solution(By Apex Team)

Average age of the class = 15 years
Average age of the class including teacher = 15 years 3 months
Teacher’s age
= 15 × 40 + $\large\frac{3}{12}$ × 40 – 15 × 39
= 610 – 585
= 25 years

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