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. Th…
Mental Ability & Logical Reasoning ·Previously asked in UPSC Civil Services Examination 2025
View the full solved paper: GS Paper II
Question
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?
- A. P
- B. Q
- C. R
- D. Cannot be concluded (Correct answer)
Correct Answer
Option D — Cannot be concluded
Detailed Solution & Explanation
The correct answer is Cannot be concluded.
Key Points
- If P stole: P's statement "I didn't steal" = false, "Q stole" = false.
- Q's statements both become "R didn't steal" (true) and "I didn't steal" (true — Q didn't steal).
- R: "I didn't steal" (true).
- P has 1 false statement — possible for a guilty person.
- If Q stole: P says "Q stole" = true, but a guilty person should have at least one false statement.
- Q says "I didn't steal" = false ✓.
- If R stole: R says "I don't know who did it" — but R knows they did it, so false.
- However multiple consistent interpretations exist.
- Answer: Cannot be concluded.