Question

the average age of parents in a family is 35 years & the average age of parents & their only son is 27 yrs .find the son's age​

Answer 1

Let age of father = x years and the age of mother = y years

Now, The average age of a father and a mother is 35 years.

$\frac{(x + y)}{2} = 35$

⇒ x + y = 70

⇒ x = 70 - y ........(1)

Let age of son = z years

Now, The average age of the father, mother and their only son is 27 years.

($\frac{x + y + z}{3} ) = 27$

⇒ x + y + z = 81

Now, putting the value of x in above equation from equation (1), we get

⇒ 70 - y + y + z = 81

⇒ 70 + z = 81

⇒ z = 81 - 70

       = 11

Hence, age of son = 11 years