1. A system which is linear is said to obey the rules of a) Scaling b) Additivity c) Both scaling and additivity 2. Should real time instruments like oscilloscopes be time invariant? a) Yes b) Sometimes c) Never 4. Most of the signals found in nature are a) Continuous-time and discrete-time c) Digital and Analog 3. For the signal x(t) = a - b exp(-ct), what is the steady state value, and the initial value? a) a, b-a b) c, c-a c) a, a-b d) b, a-b 5. Y(t) = x (2t) is a) Compressed signal c) Shifted signal d) They have no relation with time variance 8. A signal is anti-causal if a) x(t) = 0 for t = 0 c) x(t) = 1 fort > 0 b) Continuous-time and digital d) Analog and Continuous-time 7. Evaluate the following function in terms of t: a) 1 b) 1/r(t) C) 00 b) Expanded signal d) Amplitude scaled signal by a factor of 2 6. What is the necessary and sufficient condition for a sum of a periodic continuous time signal to be periodic? a) Ratio of period of the first signal to period of other signals should be constant b) Ratio of period of the first signal to period of other signals should be finite c) Ratio of period of the first signal to period of other signals should be real d) Ratio of period of first signal to period of other signal should be rational Ek-18[k]/fu(t)dt d) Homogeneity d) 1/8(t) b) x(t) = 1 fort < 0 d) x(t) = 0 fort > 0 9. If two LTI systems with impulse response h1 (t) and h2 (t) are connected in parallel then output is given by a) y(t) = x(t) [h1(t) + h2(t)] c) y(t) = x(t) [h1(t)h2(t)] b) y(t) = x(t) + [h1(t) + h2(t)] d) y(t) = [x(t) h1(t)] + h2(t) 10. Which of the following is identical to ".. 6[k] a) S[n + 1] b) u[n] c) n 8[n] d) 1