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GATE 2021 CE (CE2) – Question 5

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

P,Q,R,S sit in a row, with R forbidden from the second position from the left. How many distinct arrangements are possible?

  1. 6
  2. 9
  3. 18
  4. 24

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Show answer and explanation

Correct answer: (C) 18

Explanation

All four people can be arranged in $4!=24$ ways. Fixing R in the forbidden second position leaves $3!=6$ arrangements of the others. Subtracting gives $24-6=\mathbf{18}$ valid arrangements, **C**.