**Question:**

The average age of three boys is 25 years and their ages are in the proportion 3: 5 : 7. The age of the youngest boy is:

**Option A):**

9 years**Option B):**

21 years**Option C):**

15 years**Option D):**

18 years

**Correct Answer is Option C):**

15 years

**Explanation:****Solution:**

Total age of boys (25 X 3) years = 75 years

Age of the youngest = (75 X 3/15) = 15 years