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Unformatted text preview: 1 CHAPTER 7 SECTION 1: RANDOM VARIABLES AND DISCRETE PROBABILITY DISTRIBUTIONS MULTIPLE CHOICE 1. The weighted average of the possible values that a random variable X can assume, where the weights are the probabilities of occurrence of those values, is referred to as the: a. variance. b. standard deviation. c. expected value. d. None of these choices. ANS: C PTS: 1 REF: SECTION 7.1 2. The number of accidents that occur annually on a busy stretch of highway is an example of: a. a discrete random variable. b. a continuous random variable. c. expected value of a discrete random variable. d. expected value of a continuous random variable. ANS: A PTS: 1 REF: SECTION 7.1 3. A function or rule that assigns a numerical value to each simple event of an experiment is called: a. a sample space. b. a probability distribution. c. a random variable. d. None of these choices. ANS: C PTS: 1 REF: SECTION 7.1 4. A table, formula, or graph that shows all possible values a random variable can assume, together with their associated probabilities, is called a(n): a. discrete probability distribution. b. discrete random variable. c. expected value of a discrete random variable. d. None of these choices. ANS: A PTS: 1 REF: SECTION 7.1 5. Which of the following are required conditions for the distribution of a discrete random variable X that can assume values x i ? a. 0 p ( x i ) 1 for all x i b. p ( x i ) = 1 all x i c. Both a and b are required conditions. d. Neither a nor b are required conditions. ANS: C PTS: 1 REF: SECTION 7.1 2 6. Which of the following is not a required condition for the distribution of a discrete random variable X that can assume values x i ? a. 0 p ( x i ) 1 for all x i b. p ( x i ) = 1 all x i c. p ( x i ) &gt; 1 for all x i d. All of these choices are true. ANS: C PTS: 1 REF: SECTION 7.1 7. In the notation below, X is the random variable, c is a constant, and V refers to the variance. Which of the following laws of variance is not true? a. V ( c ) = 0 b. V ( X + c ) = V ( X ) + c c. V ( cX ) = c 2 V ( X ) d. None of these choices. ANS: B PTS: 1 REF: SECTION 7.1 8. Which of the following is a discrete random variable? a. The Dow Jones Industrial average. b. The volume of water in Michigan Lakes. c. The time it takes you to drive to school. d. The number of employees of a soft drink company. ANS: D PTS: 1 REF: SECTION 7.1 9. Which of the following is a continuous random variable? a. The number of employees of an automobile company. b. The amount of milk produced by a cow in one 24hour period. c. The number of gallons of milk sold at Meijer grocery store last week. d. None of these choices. ANS: B PTS: 1 REF: SECTION 7.1 10. A lab in Michigan State University orders 100 rats a week for each of the 52 weeks in the year for experiments that the lab conducts. Suppose the mean cost of rats used in lab experiments turned out to be $15.00 per week. Interpret this value....
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This note was uploaded on 09/28/2010 for the course FINOPMGT 250 taught by Professor Kumar during the Spring '10 term at University of Massachusetts Boston.
 Spring '10
 Kumar

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