Midterm_Sample

# Midterm_Sample - The Hong Kong University of Science and...

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The Hong Kong University of Science and Technology Department of Electronic and Computer Engineering ELEC 210: Probability and Random Processes in Electrical Engineering 2010 Fall Semester Midterm Test October 20, 2010 Name: Student ID: Instructions: 1. This is an 80-minute test. 2. You may use a non-programmable calculator. 3. There are 2 sections : a. Section 1: 10 Multiple Choice Questions b. Section II: 4 Problems 4. Try to attempt all questions. 5. Answer each question in your answer booklet . 6. The distribution of marks is shown in the table below: Question Mark Multi. Choice 10 1 10 2 10 3 10 4 10 Total 50

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SECTION I: Multiple Choice [10 Marks] Notes: For each multiple-choice question below, select only ONE answer. Write your answer in your ANSWER BOOKLET (not this question sheet) [1 Mark Per Question] 1. For a discrete random variable, X , which of the following statements is not true? a) We can evaluate all moments of X solely based on the probability mass function b) The standard deviation of X has the same units as the mean c) All moments of X are non-negative d) The conditional mean and variance of X (conditioned on some event A) are examples of moments. e) Trellis diagrams, which represent the decoder of a Trellis Coded Modulation communication system, implement successive products of conditional probabilities. 2. Which of the following statements about conditional probability is not true? a) Conditioning always increases the probability of an event b) Conditioning may increase or decrease the probability of an event c) Conditioning changes the effective sample space of the experiment d) The Total Theorem of Probability allows one to compute unconditional probabilities by combining conditional probabilities 3. Assume that we select balls from an urn, at random. From the following selection methods, which method does not lead to equally-probable events? a) With replacement with ordering b) Without replacement with ordering c) With replacement without ordering d) Without replacement without ordering 4. If two events have non-zero probabilities and are mutually exclusive, then they: a) Must be independent b)
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## This note was uploaded on 10/16/2011 for the course ELEC 308,315,10 taught by Professor Prof.shenghuisong during the Spring '11 term at CUHK.

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Midterm_Sample - The Hong Kong University of Science and...

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