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GATE 2019 CS – Question 6

General Aptitude · Analytical Aptitude: Logical Reasoning and Deduction · 2 marks · Multiple choice

The police arrested four criminals – P, Q, R and S. The criminals knew each other. They made the following statements:

P says "Q committed the crime."

Q says "S committed the crime."

R says "I did not do it."

S says "What Q said about me is false."

Assume only one of the arrested four committed the crime and only one of the statements made above is true. Who committed the crime?

  1. P
  2. R
  3. S
  4. Q

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Show answer and explanation

Correct answer: (B) R

Explanation

Try R as the criminal. Then P is false (it was not Q), Q is false (it was not S), R is false (R did it), and S, who says Q's statement is false, is true. Exactly one statement is true, so R committed the crime. The other suspects lead to two or more true statements.