The age of the father 10 years ago was thrice the age of his son. Ten years hence, the father's age will be twice that of his son. What is the ratio of their present ages?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is Option 2 i.e. 7 : 3.
Let the present age of the father and his son be F and S
Given that,
The age of the father 10 years ago was thrice the age of his son
⇒ (F - 10) = 3 (S - 10)
⇒ F - 10 = 3S - 30
⇒ 3S - F = 20 .....(1)
Now, Ten years hence, the father's age will be twice that of his son
⇒ F + 10 = 2 (S + 10)
⇒ F - 2S = 10 ......(2)
Equation (1) + Equation (2)
⇒ S = 30 years
From Equation (2)
⇒ F - 60 = 10
⇒ F = 70 years
Hence, the required ratio = 70 : 30 = 7 : 3