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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.

Answer & Solution
Correct Answer: Option D
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
Examveda
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4 Comments
Priti Saraf
Priti Saraf 5 years ago
@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.
Priti Saraf
Priti Saraf 5 years ago
@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.
Kishor Chandra
Kishor Chandra 5 years ago
Before birth of youngest the member shud be reduced to 9. So the total age 90. Avg age 90/9=10
Sourov Roy
Sourov Roy 6 years ago
200 - 10 × 10 how did the 10*10 come