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GATE 2021 IN – Question 6

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

Statement: Either P marries Q or X marries Y. Which option is its logical negation?

  1. P does not marry Q and X marries Y
  2. Neither P marries Q nor X marries Y
  3. X does not marry Y and P marries Q
  4. P marries Q and X marries Y

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Show answer and explanation

Correct answer: (B) Neither P marries Q nor X marries Y

Explanation

Write the statement as A∨B, where A means P marries Q and B means X marries Y. De Morgan’s law gives ¬A∧¬B: **neither P marries Q nor X marries Y, B**. Negation requires both alternatives to be false.