The sum of the present ages of Rohit and Ankit is 78 years. If Rohit's present age is twice the present age of Ankit, what is Rohit's age (in years)?

Introduction / Context:
This is a straightforward aptitude question on ages involving a sum and a simple multiple relationship. We are given the total of the ages of Rohit and Ankit, and we know that Rohit is twice as old as Ankit. Our task is to find Rohit's present age.

Given Data / Assumptions:

- The sum of the present ages of Rohit and Ankit is 78 years.
- Rohit's present age is twice Ankit's present age.
- All ages are in years and positive.

Concept / Approach:
We can solve this problem using simple algebra. By representing Ankit's age with a variable and expressing Rohit's age as a multiple of that variable, we can use the given sum to form and solve a linear equation. This method is common in introductory questions on ratios and ages.

Step-by-Step Solution:
Step 1: Let Ankit's present age be A years. Step 2: Rohit's present age is twice Ankit's age, so Rohit's age = 2A years. Step 3: The sum of their present ages is given as 78 years, so A + 2A = 78. Step 4: Combine like terms to obtain 3A = 78. Step 5: Divide both sides by 3 to get A = 78 / 3 = 26 years. Step 6: Rohit's present age = 2A = 2 × 26 = 52 years.

Verification / Alternative check:
We can quickly verify the result. If Ankit is 26 years old and Rohit is 52 years old, then the sum of their ages is 26 + 52 = 78 years, exactly as stated in the question. Also, 52 is twice 26, which matches the requirement that Rohit's age is twice Ankit's age. Therefore, the answer is consistent with all given conditions.

Why Other Options Are Wrong:
Values like 48 years, 54 years or 60 years would not satisfy both conditions simultaneously. For example, if Rohit were 48 years old, Ankit would have to be 30 years old to sum to 78, and 48 is not twice 30. Similar inconsistencies arise for the other incorrect options. Only 52 years satisfies both the sum and the "twice as old" relationship.

Common Pitfalls:
Some students may mistakenly divide 78 directly by 2, assuming both persons are the same age, or they might misinterpret the phrase "twice the age" and set up a wrong equation. Carefully defining a variable for one person's age and then expressing the other in terms of that variable helps avoid such errors.

Final Answer:
Rohit's present age is 52 years.