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Random Signal Analysis : Question Paper May 2012 - Electronics & Telecomm. (Semester 5) | Mumbai University (MU)

## Random Signal Analysis - May 2012

### Electronics & Telecomm. (Semester 5)

TOTAL MARKS: 80
TOTAL TIME: 3 HOURS
(1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks.
1 (a) If A and B are any two events, then prove that P(A∪B)=P(A)+P(B)-P(A?B)(5 marks) 1 (b) Explain the concept of conditional probability with an example(5 marks) 1 (c) State and prove Baye's Theorem and Total Probability Theorem(10 marks) 2 (a) Define discrete and continuous random variables, give one example of each type. Define exception of discrete random variable and continuous random variable(10 marks) 2 (b) Suppose two million lottery tickets are issued with 100 winning tickets among them.
(i) If a person purchase 100 ticket, what is the probability of winning?
(ii) How many tickets should one buy to be 95% confident of having a winning ticket?
(10 marks)
3 (a) Find the characteristics function of Poisson distribution and find it's mean and variance(10 marks) 3 (b) Let X be a random variable with CDF Fx(x) and PDF f(x)(x). Let y=aX+B where a and b are real constant and a ≠0. Fid PDF of y in terms of Fx(x)(10 marks) 4 (a) Suppose that X and Y are continues random varibles with Joint Probability Density function
$$f_{xy}(x,y)=\dfrac {xe^{-y}}{2}; \ \ 0<x<2, \ \ y>0$$ $$=0 \ \ elsewhere$$
(10 marks)
4 (b) (ii) Find the join cumulative distribution function of X and Y
Find the marginal probability density functions of X and Y.
(10 marks)
5 (a) Define Central Limit Theorem and give its significance(5 marks) 5 (b) Describe sequence of ramdom variables(5 marks) 5 (c) IF two random variable are independent then prove that the density of their sum equals the convolution of their density functions.(10 marks) 6 (a) Consider a random process X(t) defined by X(t)=A Cos(ωt+θ); -∞<t<∞ where A and ω are constant and θ is a uniform random variable over (-π, π). Show that X(t) is WSS(10 marks) 6 (b) Prove that if the input to a linear time invaiant system is WSS then the output is also WSS(10 marks) 7 (a) Explain power spectral density. State its important properties and prove any one property(10 marks) 7 (b) State and prove the Chapman-Kolmogorov equation.(10 marks)

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