UPPCL 2013

Question

Can anybody explain this question ??

Answer 1

Logic 1 exists for the given sets of inputs of A,B,C and D means when we have the codes out of the ones mentioned in the question , we get 1 as output..This is nothing but a behaviour of minterm.

So we can write the Canonical Sum Of Products(SOP) expression for the given sets of minterms.

So, 

0010 will correspond to A'B'CD'

1000 will correspond to AB'C'D'

1011 will correspond to AB'CD  and

1111 will correspond to ABCD.

So minterm expansion (or) canonical SOP using above minterms can be written as :

F = A'B'CD' + AB'C'D' + AB'CD + ABCD

   = A'B'CD' + AB'C'D' + A(B + B')CD

   = A'B'CD' + AB'C'D' + ACD

Hence B) option should be correct.The option given in the answer key is wrong here. 

Comments

then (A) should also be correct ??

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Actually the question is not clear and correct.

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@payal,  Most Appropriate Answer is Option B. Or you can say , we always choose strong answer(simplification form)