In a family, the average age of a father and a mother is 35 years. The average age of the father, mother and their only son is 27 years. What is the age of the son?
1). 12 years
2). 11 years
3). 10.5 years
4). 10 years
The average age of a father and a mother is 35 years.
The sum of their (father and mother) ages = 35 × 2 = 70 = S (say)
The average age of the father, mother and their only son is 27 years.
The sum of their ages = 27 × 3 = 81
⇒ S + age of son = 81
⇒ Age of son = 81 – S = 81 – 70 = 11 years.