The average age of a family of 5 members is 20 years. If the age of the youngest member be 10 years then what was the average age of the family at the time of the birth of the youngest member?
Choose the correct choice from the following answers:  A) 13.5  B) 14  C) 15  D) 12.5  E) None
Solution:   At present the total age of the family = 5*20= 
<gadget id="calculator">5*20</gadget>
<output>100</output>
100.   The total age of the family at the time of the birth of the youngest member,=[100−10−(10*4)]=50.   Therefore, average age of the family at the time of birth of the youngest member,   = 50/4 = 12.5.   Answer: Option 12.5
<result>D</result>
The average age of a family of 5 members is 20 years. If the age of the youngest member be 10 years then what was the average age of the family at the time of the birth of the youngest member?