UPSC Prelims 2005 Q92: Science & Technology – Logical Reasoning & Puzzles
Which is Krishnan’s hometown?
- (a) Ahmedabad
- (b) Cuttack
- (c) Bhopal
- (d) Cannot be determined
Answer: (c) Bhopal
Explanation
Logic puzzle: Krishnan's hometown
| Clue | Deduction |
|---|---|
| (i) Gopal's hometown is Ernakulam; (iv) Inder's is Cuttack | Two hometowns fixed |
| (vi) History College is in Jai's hometown Ahmedabad | Jai's hometown is Ahmedabad |
| Left: Bhopal and Delhi for Harsh and Krishnan | (v) Krishnan studies in Delhi, so Delhi cannot be his hometown |
| Result | Krishnan's hometown is Bhopal and Harsh's is Delhi |
Five boys Gopal, Harsh, Inder, Jai and Krishnan have Ahmedabad, Bhopal, Cuttack, Delhi and Ernakulam as hometowns and study in Engineering, Medical, Commerce, Economics and History colleges, each in one of these cities but never in his own hometown. From the clues, Gopal (Ernakulam), Inder (Cuttack) and Jai (Ahmedabad) are fixed. Bhopal and Delhi remain for Harsh and Krishnan, and since Krishnan studies in Delhi, his hometown must be Bhopal.
Answer: (c) Bhopal.
Why each option is right or wrong
- (a) Incorrect. Ahmedabad is Jai's hometown.
- (b) Incorrect. Cuttack is Inder's hometown.
- (c) CORRECT. Bhopal is the only hometown left for Krishnan.
- (d) Incorrect. The clues fix the answer.
Key point
Fix the stated hometowns first; the rule 'not in own hometown' removes Delhi for Krishnan.
Remember
Krishnan studies in Delhi, so his hometown is Bhopal.
Common mistakes
- Ignoring the rule that nobody studies in his own hometown.
- Leaving Bhopal and Delhi open for Krishnan.
- Not tabulating the clues in a grid first.
Exam tip
Draw a grid of boys against cities and strike out impossible cells.
Sources
- R. S. Aggarwal — A Modern Approach to Verbal and Non-Verbal Reasoning (Puzzle Test)
- Arun Sharma — How to Prepare for Logical Reasoning for the CAT (arrangement and matching puzzles)