The average age of 3 girls is 20 years and their ages are in the proportion 3 : 5 : 7. the age of youngest girl is?
Correct Answer: 12 years
Explanation:
Their total age = (3 x 20) yeras = 60 years
Let their ages be 3x, 5x and 7x years.
Then 3x + 5x + 7x = 60
⇒ x = 4
∴ yongest girl is = 3x = 12 years old.
