The expected answers were:
(a) The truth table for the logic circuit as is as shown below.
| A |
B |
C |
F |
0 |
0 |
1 |
0 |
0 |
1 |
1 |
1 |
1 |
0 |
1 |
0 |
1 |
1 |
0 |
0 |
(b) The Boolean expression that relates the output to the input is
F = (A.B) . B = C.B
(c) As can be seen from the truth table, F is at the logic level 1 only when A = 0 and B = 1. The equation was on digital electronics. The question was popular with the candidates. Quite a few candidates gave more than four correct responses.
