Question

 5 years ago, the ratio of the ages of Mohit and Rohan was 5 : 6 . After seven years the ratio of their ages will be 11 : 12 . find the Rohan's present age.

1. 17 years 
2. 18 years 
3. 19 years 
4. 20 years 
5. None of these

Answer 1

Correct Answer - Option 1 : 17 years 

Given 

5 years ago, ages of mohit and rohan = 5 : 6

7 years after, ages of mohit and rohan = 11 : 12

Calculation:

Present age of mohit = 5x + 5 .

Present age of rohan = 6x + 5

After 7 years in future, their ages will be 5x + 5 + 7 and 6x + 5 + 7 respectively

According to question,

⇒ (5x + 12)/(6x + 12) = 11/12

⇒ 60x + 144 = 66x + 132

⇒ 6x = 12

⇒ x = 2

So, the present age of rohan = 6x + 5 = 12 + 5 = 17 years

∴ The required answer is 17 years