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GATE 2021 CE (CE1) – Question 5

General Aptitude · Analytical Aptitude: Logical Reasoning and Deduction · 1 mark · Multiple choice

Four persons P, Q, R and S are seated in a row facing the same direction. P and R cannot sit adjacent, and S must sit to the right of Q. How many distinct arrangements are possible?

  1. 2
  2. 4
  3. 6
  4. 8

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Show answer and explanation

Correct answer: (C) 6

Explanation

There are $4!=24$ arrangements. Treating adjacent P,R as a block gives $2(3!)=12$ forbidden arrangements, leaving 12. Swapping Q and S pairs the valid arrangements, and exactly one in each pair has Q before S. Thus **6 (C)** remain.