Problems on Ages — “Ramu is 48. Robin is 6 years younger than Ramu and 14 years older than Rohit. Ramu has two children (Neethu and Vinu). Rohit’s youngest sister is Krishna, who is 15 years younger than him. Find Krishna’s present age.”

Introduction / Context:
This is a chain-logic ages problem. We are given one fixed age (Ramu) and a sequence of older/younger relationships connecting Robin, Rohit, and finally Krishna. Carefully traversing these links and keeping operations in the correct order yields Krishna’s age without any guesswork.

Given Data / Assumptions:

• Ramu = 48 years (fixed).
• Robin is 6 years younger than Ramu ⇒ Robin = 48 − 6.
• Robin is 14 years older than Rohit ⇒ Rohit = Robin − 14.
• Krishna is 15 years younger than Rohit ⇒ Krishna = Rohit − 15.
• All ages are present ages and non-negative integers.

Concept / Approach:
Translate each statement into a simple addition/subtraction. Start from Ramu’s known age, compute Robin, then Rohit, then finally Krishna. No ratios or averages are involved, so linear offsets are enough.

Step-by-Step Solution:

Verification / Alternative check:
Check back up the chain: Krishna 13 ⇒ Rohit 28 is indeed 15 older; Robin 42 is 14 older than Rohit; Ramu 48 is 6 older than Robin. All relations hold.

Why Other Options Are Wrong:
12/14/15/16 fail at least one of the linked differences when cross-checked from Ramu down to Krishna.

Common Pitfalls:
Reversing “older/younger” operations; mixing up who is older than whom; skipping a link in the chain and doing a one-step jump that ignores an intermediate relationship.

Final Answer:
13