3 year ago, the average of a family of 5 members was 17 years. A baby having been born, the average age of the family is the same today. The present age of the baby is

Solution :
Total age of 5members, 3 years ago = (17 x 5) years = 85 years.
Total age of 5 members now = (85 + 3 x 5) years      = 100 years.
Total age of 6 members now = (17 x 6) years            = 102 years.
     Age of the baby = (102 – 100) years                   = 2 years.