Question

Ten years ago, average of the ages of a men and his wife was 25 years. Today the average age of these two and their son, taken together is again 25 years. What is the age (in years) of the son today?

• A. $2$
• B. $5$
• C. $8$
• D. $10$

Answer 1

Answer: (B)

$5$

let the age of the wife be $w$ and

the age of the husband be $h$

Given that the average age of husband and wife is $25$

Therefore, $25=\frac{w+h}{2}$

$⟹w+h=50$ -----(1)

After ten years age of the wife is $w+10$ and the

age of the husband after ten years is $h+10$

let the son age be $x$ year.

Given that the average age of family is $25$

Therefore, $25=\frac{(w+10)+(h+10)+x}{3}$

$⟹75=w+h+20+x$

$⟹w+h+x=55$ ------(2)

substituting (1) in (2) we get

$⟹50+x=55$

$⟹x=5$

Therefore, the age of the son is $5$ years.