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GATE 2020 ME (ME1) – Question 7

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

P, Q, R and S are to be uniquely coded using $\alpha$ and $\beta$. If P is coded $\alpha\alpha$ and Q is coded $\alpha\beta$, then R and S, respectively, can be coded as ______.

  1. $\beta\alpha$ and $\alpha\beta$
  2. $\beta\beta$ and $\alpha\alpha$
  3. $\alpha\beta$ and $\beta\beta$
  4. $\beta\alpha$ and $\beta\beta$

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Correct answer: (D) $\beta\alpha$ and $\beta\beta$

Explanation

Two positions and two symbols give four codes: αα, αβ, βα, ββ. P and Q already use the first two. R and S must use the remaining two without repetition, which is the pair in **D**.