### The average age of three boys is 15 years. If their ages are in ratio 3 : 5 : 7, the age of the youngest boy is.

**A.** 21 years

**B.** 18 years

**C.** 15 years

**D.** 9 years

## Show Answer

###
Answer-D

Solution-

__Solution(By Apex Team)__

Sum of ages of three boys = 45 years
Now,
$\begin{array}{l}\text{(3x + 5x + 7x) = 45}\\
\text{⇒ 15x = 45}\\
\text{⇒ x = 3}\\
\text{So,}\\
\text{age of youngest boy = 3x}\\
\text{= 3 × 3}\\
\text{= 9 years}\end{array}$