Consider the 4-to-1 multiplexer with two select lines \(S_1\) and \(S_0\)…

2014

Consider the 4-to-1 multiplexer with two select lines \(S_1\) and \(S_0\) given below

The minimal sum-of-products form of the Boolean expression for the output \(F\)of the multiplexer is

  1. A.

    \(\bar{P}Q + Q\bar{R} + P\bar{Q}R\)

  2. B.

    \(\bar{P}Q + \bar{P}Q\bar{R} + PQ\bar{R} + P\bar{Q}R\)

  3. C.

    \(\bar{P}QR + \bar{P}Q\bar{R} + Q\bar{R} + P\bar{Q}R\)

  4. D.

    \(PQ\bar{R}\)

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Correct answer: A

Correct. With S1 = P and S0 = Q, the 4-to-1 MUX gives F = I0 P'Q' + I1 P'Q + I2 P Q' + I3 P Q. Substituting I0=0, I1=1, I2=R, I3=R' yields F = P'Q + P Q' R + P Q R'. By grouping prime implicants the minimal sum-of-products is F = P'Q + Q R' + P Q' R (this matches the given expression).

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