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  Choices:
A) 21 years	B) 18 years	C) 15 years	D) 9 years	E) None
Solution: Sum of ages of three boys = 45 years   Now, (3x+5x+7x) = 45   Or, 15x = 45   Or, x = 3   So, age of youngest boy = 3x = 3*3= 
<gadget id="calculator">3*3</gadget>
<output>9</output>
9 years.   Answer: Option 9 years
<result>D</result>
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