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

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

A. 20
B. 21
C. 28
D. 32

A. 18
B. 20
C. 24
D. 30

A. 10 years
B. 10.5 years
C. 11 years
D. 12 years