The average age of a family of 10 members is 20 years. If the age of the youngest member of the family is 10 years, then the average age of the members of the family just before the birth of the youngest member was approximately.
A. 27.14 years
B. 12.5 years
C. 14.28 years
D. $$11\frac{1}{9}$$ years
Answer: Option D
Solution(By Examveda Team)
According to the question,Average age of a family of 10 members is = 20 years
Sum of the age of 10 members
= 20 × 10 = 200 years
If the age of youngest member is = 10 years
Sum of the age of 9 members at the time of birth of youngest member
= 200 - 10 × 10
= 200 - 100
= 100 years
∴ Average of 9 members is
= $$\frac{100}{9}$$ = $$11\frac{1}{9}$$ years
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Comments ( 4 )
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@sourov we are going back 10 years. so we have to deduct the total age of 10 members through this 10 years to arrive at the total of 10 years back.
@kishor when we are deducting (10*10), we are reaching to the time when the youngest member was just born. So the total of 100 is the total of the then present 9 family members.
Before birth of youngest the member shud be reduced to 9. So the total age 90. Avg age 90/9=10
200 - 10 × 10 how did the 10*10 come