JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II PROBABILITY THEORY AND STOCHASTIC PROCESSES Previous Question Paper (December - 2018 - R16)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks.
Part A
State theorem of total probability.
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If a set of events B1, B2, ..., Bn forms a partition of the sample space S such that they are mutually exclusive and collectively exhaustive, then for any event A, the total probability is given by:
Explain the terms events and mutually exclusive events with examples.
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An event is a subset of the sample space representing a specific outcome or combination of outcomes of a random experiment, such as rolling a 3 on a die. Mutually exclusive events are events that cannot occur simultaneously; if one occurs, the other cannot. For example, in a coin toss, getting a 'Head' and a 'Tail' are mutually exclusive events.
Define skew of a random variable.
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Write the properties of probability density function.
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Write the expressions to obtain marginal distribution functions from joint density function.
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State central limit theorem for unequal distributions.
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Explain strict sense stationarity of a random process.
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Write short notes on Poisson random process.
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Write Wiener- Khintchine relations.
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Is the function represented a valid power spectral density? Mention properties used.
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Part B
State and prove Bayes theorem.
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Discuss relative frequency approach of probability.
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A pointer is spun on a fair wheel of chance having its periphery labeled between 1 and 100. i) What is the probability that the pointer will stop between 20 and 35? ii) What is the probability that the wheel will stop on 58.
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Classify random variables and explain.
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Find the mean of Poisson random variable.
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A random variable X is uniformly distributed in the interval (-2,2). It is transformed to a new variable Y by the transformation Y = CX2. Obtain the density of Y.
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In a sports event javelin throw distances are well approximated by a Gaussian distribution for which mean is 30m and standard deviation is 5m. In a qualifying round, contestants must throw farther than 26m to qualify. In the main event the record throw is 42m. i) What is the probability of being disqualified in the first round? ii) In the main event what is the probability the record will be broken?
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Obtain the characteristic function for Binomial random variable.
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Derive the expression for conditional density considering interval conditioning.
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The random variables Y1, Y2, X1, X2 are related by the relations: Y1 = aX1 - bX2 and Y2 = cX1 - dX2. Find fY1,Y2(y1,y2) in terms of joint density of X1 and X2.
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Check for the validity of joint distribution GX,Y(x,y) = u(x)u(y)[1 - e-(x+y)]. Mention the properties used.
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Prove that the mean of weighted sum of random variables is equal to the weighted sum of means of the individual random variables.
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State and prove any three properties of Auto correlation function of a random process.
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A random process X(t) = A Cos(ω0t + Θ) where A and ω0 are constants and Θ is a uniformly distributed random variable in (0,π), check whether random process is WSS or not?
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X(t) is W.S.S. random process and X(t) = A Cos(w0t + Θ). Given A is a uniformly distributed random variable in the interval (-a, b). Find E[X(t)], RXX(t,t+τ).
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Define cross correlation function and write its properties.
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Derive the relation between input and output power spectral densities of an LTI system.
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Derive the relationship between cross power spectrum and cross correlation function.
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