The sum of ages of 5 children born at the intervals of 3 years each is 50 years. What is the age of the youngest child?
4 years
8 years
10 years
None of these
Explanation:
Let the ages of children be $ x $, $\left( x + 3\right)$, $\left(x + 6\right)$, $\left(x + 9\right)$ and $\left(x + 12\right)$ years.
Then, $ x $ + $\left(x + 3\right)$ + $\left(x + 6\right)$ + $\left(x + 9\right)$ + $\left(x + 12\right)$ = 50
$\Rightarrow$ 5$ x $ = 20
$\Rightarrow x $ = 4.
$\therefore$ Age of the youngest child = $ x $ = 4 years.