A mobile phone has been stolen. There are 3 suspects P, Q and R. They were questioned knowing that only one of them is guilty. Their responses are as follows:
- P.I did not steal. Q stole it.
- Q.R did not steal. I did not steal.
- R.I did not steal. I do not know who did it.
Who stole the mobile phone?
Answer & explanation
Answer: (d) Cannot be concluded
The item gives no rule about who tells the truth. Even if we assume every innocent person speaks the truth, both 'P stole' and 'Q stole' fit all the statements, so the thief cannot be identified.
- The item says only one person is guilty but gives no rule on who tells the truth or lies.
- Test the most helpful assumption: innocent people speak the truth. If R stole, innocent P's claim 'Q stole it' would be false — so R is ruled out.
- If P stole: innocent Q says R and Q did not steal (true), and innocent R says he did not steal (true). Consistent.
- If Q stole: innocent P says he did not steal and Q stole it (true), and innocent R's statements are true. Consistent.
- Both P and Q remain possible, so the thief cannot be concluded.
Remember · In truth-and-lie puzzles, test each suspect as culprit for consistency; if more than one survives, the answer is 'cannot be concluded'.
Question and answer: UPSC's official GS Paper II (2025, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·