Correct Answer - Option 3 : 20 yrs
Given:
Average age of 5 members = 21 years
Age of youngest child = 5 years
Formula used:
Average =(Sum of values)/(Total number of values)
Calculation:
Sum of the age of 5 members = 21 × 5 = 105
5 years ago, each member’s age is reduced by 5
Total reduction in sum = 105 – 5(5) = 80
Number of reduced family members = 5 – 1 = 4
Average = 80/4 = 20
∴ The average age of the family at the time of his birth is 20 years.
