Pass/Fail Exam Logic Puzzle

CAT 1992 Slot 1 · DILR · Hard · Logical Deduction

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Each of three friends knows whether the other two have passed or failed in an examination, but does not know his own result. The teacher comes and says, "At least one has failed". If all three still do not know their own results, which of the following is true?

  1. A.

    One student has failed.

  2. B.

    Two students have failed.

  3. C.

    Two or more students have failed.

  4. D.

    All three have failed.

Answer

C

Explanation

If only one had failed, then the person who had failed would have seen that the other two passed, and thus realized that he was the failed one. But since no one still knows his own result, two or more students must have failed.

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