The average age of a husband and a wife was 27 years when the child was born. The average age of the husband, the wife and a new born child is 21 years now. The present age of the child is:

3 years

According to the question = Husband+ wife = 27 × 2 = 54

Husband + wife + child = 21 × 3 = 63

Husband + wife + child = (husband + wife + child) - (Husband + wife) = 63 - 54 = 9 years increase

 So, 9 years divide among husband, wife and child equally

Age of child = 3 years