The average age of a class of 39 students is 15 years. If the age of the teacher be included, then the average increases by3 months. Find the age of the teacher. Choose one.
A) 22 years  B) 23 years  C) 24 years  D) 25 years  E) 26 years
avg of 39 student = 15 yrs   Total age of 39 students=39*15= 
<gadget id="calculator">39*15</gadget>
<output>585</output>
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 yrs   so the total age of (39 student+1 teacher) or 40 persons=   40*15.25= 
<gadget id="calculator">40*15.25</gadget>
<output>610</output>
610 yrs   so age of teacher=610-585= 
<gadget id="calculator">610-585</gadget>
<output>25</output>
25 years   ANSWER:25 years
<result>D</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 by3 months. Find the age of the teacher.