The average age of a husband and his wife was 23 years at the time of their marriage. After five years they have a one year old child. What is the average age of the family ?

Solution:
Total of the age of husband and wife = 2×23=46
Total of the age of husband and wife after 5 years + Age of the 1 year old child
                                                      = 46+5+5+1=57
Average age of the family = 57 / 3
                                       = 19