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==Question==
 
==Question==
'''Part 1. '''
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1 (33 points)
  
Write Statement here
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Let <math class="inline">\mathbf{X}</math>  and <math class="inline">\mathbf{Y}</math>  be two joinly distributed random variables having joint pdf
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<math class="inline">f_{\mathbf{XY}}\left(x,y\right)=\left\{ \begin{array}{lll}
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1, &  & \text{ for }0\leq x\leq1\text{ and }0\leq y\leq1\\
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0, &  & \text{ elsewhere. }
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\end{array}\right.</math>
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 +
(a)
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Are <math class="inline">\mathbf{X}</math>  and <math class="inline">\mathbf{Y}</math>  statistically independent? Justify your answer.
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 +
 
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(b)
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Let <math class="inline">\mathbf{Z}</math>  be a new random variable defined as <math class="inline">\mathbf{Z}=\mathbf{X}+\mathbf{Y}</math> . Find the cdf of <math class="inline">\mathbf{Z}</math> .
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 +
(c)
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Find the variance of <math class="inline">\mathbf{Z}</math> .
  
 
:'''Click [[ECE_PhD_QE_CNSIP_Jan_2006_Problem1.1|here]] to view student [[ECE_PhD_QE_CNSIP_Jan_2006_Problem1.1|answers and discussions]]'''
 
:'''Click [[ECE_PhD_QE_CNSIP_Jan_2006_Problem1.1|here]] to view student [[ECE_PhD_QE_CNSIP_Jan_2006_Problem1.1|answers and discussions]]'''

Revision as of 09:21, 10 March 2015


ECE Ph.D. Qualifying Exam

Communication, Networking, Signal and Image Processing (CS)

Question 1: Probability and Random Processes

January 2006



Question

1 (33 points)

Let $ \mathbf{X} $ and $ \mathbf{Y} $ be two joinly distributed random variables having joint pdf

$ f_{\mathbf{XY}}\left(x,y\right)=\left\{ \begin{array}{lll} 1, & & \text{ for }0\leq x\leq1\text{ and }0\leq y\leq1\\ 0, & & \text{ elsewhere. } \end{array}\right. $

(a)

Are $ \mathbf{X} $ and $ \mathbf{Y} $ statistically independent? Justify your answer.


(b)

Let $ \mathbf{Z} $ be a new random variable defined as $ \mathbf{Z}=\mathbf{X}+\mathbf{Y} $ . Find the cdf of $ \mathbf{Z} $ .

(c)

Find the variance of $ \mathbf{Z} $ .

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Part 2.

Write question here.

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Part 3.

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Part 4.

Write question here.

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