The average age of a class of 39 students is 15 years. If the age of the teacher be included, then the average increases by 3 months. Find the age of the teacher.
Choose the correct choice from the following options.
A) 22  B) 25  C) 97  D) 27  E) 91
Answer: 25 y   Explanation:   Average age of 39 students = 15 yrs   Total age of 39 students = 39 × 15 = 585 yrs   Avg age of 39 students + teacher =15+ (3/12)= 
<gadget id="calculator">15+ (3/12)</gadget>
<output>61/4 = around 15.25</output>
15.25 years   So the total age of (39 student + 1 teacher) or 40 persons= 40 × 15.25 = 610 years   So age of teacher = 610 – 585 = 25 years   Answer:25
<result>B</result>
The average age of a class of 39 students is 15 years. If the age of the teacher be included, then the average increases by 3 months. Find the age of the teacher.