Revision as of 10:21, 10 March 2015 by Lu311 (Talk | contribs)


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} $ .

Click here to view student answers and discussions

Part 2.

Write question here.

Click here to view student answers and discussions

Part 3.

Write question here.

Click here to view student answers and discussions

Part 4.

Write question here.

Click here to view student answers and discussions

Back to ECE Qualifying Exams (QE) page

Alumni Liaison

Have a piece of advice for Purdue students? Share it through Rhea!

Alumni Liaison