Correct Answer - Option 1 : 1
Given: The average age of a family of 6 members 4 yrs ago was 25 yrs. A child was born in this family and still the average age of the whole family is same today.
Formula: Average of n numbers a1, a2, .… an = (a1 + a2 + ... + an)/n
Calculation:
After 4 years the age of every member of the family increases by 4 years.
Total present age of a family of 6 members = 25 × 6 + 4 × 6 = 174
Total present age of a family including child = 25 × 7 = 175
Hence present age of child = 175 – 174 = 1 yr
