question_answer

Figure gives a system of logic gates. From the study of truth table it can be found that to produce a high output (1) at R, we must have

A) \[X=0,\,\,Y=1\] 

B)        \[X=1,\,\,Y=1\]

C) \[X=1,\,\,Y=0\] 

D)        \[X=0,\,\,Y=0\]

Correct Answer: C

Solution :

[c] The truth table can be written as

X	Y	\[\bar{X}\]	\[\bar{Y}\]	\[P=\bar{X}+Y\]	\[Q=\overline{X.Y}\]	\[R=\overline{P+Q}\]
0	1	1	0	1	1	0
1	1	0	0	1	1	0
1	0	0	1	0	0	1
0	0	1	1	1	1	0

Hence \[X=1,\] \[Y=0\] gives output \[R=1\]