Exam 4: Discrete Random Variables and Probability Distributions

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The binomial distribution is widely used in business and economic applications involving the probability of discrete occurrences.

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Given a binomial variable with n = 40 and the probability of a success on any given trial of 0.8,the mean of the probability distribution would be 0.4.

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Calculate the variances of X and Y.

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Flipping a coin is an example of a random variable.

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THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING: The manager of a movie rental store was interested in examining the relationship between the weekly take-home pay for a family and the amount that family spends weekly on recreational activities.The following output was generated using Minitab: Covariances THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING: The manager of a movie rental store was interested in examining the relationship between the weekly take-home pay for a family and the amount that family spends weekly on recreational activities.The following output was generated using Minitab: Covariances     Let X = weekly take-home pay,and Y = amount spent weekly on recreational activities. -Identify the variance of weekly take-home pay. Let X = weekly take-home pay,and Y = amount spent weekly on recreational activities. -Identify the variance of weekly take-home pay.

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The Poisson distribution can be used to approximate the binomial distribution when the number of trials n is large,and the probability P is small.

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Calculate the expected values of X and Y.

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You can use the Poisson distribution to approximate the binomial distribution with mean nP when P is small and n is large,such that nP is of only moderate size (preferably nP ≤ 7).

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If the covariance between two variables is zero,then the two variables are statistically independent.

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THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING: The following table presents the probability distribution function for the number of claims processed per hour at an insurance agency. THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING: The following table presents the probability distribution function for the number of claims processed per hour at an insurance agency.    -What is the variance of the number of claims processed? -What is the variance of the number of claims processed?

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THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING: Suppose you know that the number of complaints coming into a phone center averages 4.2 every ten minutes.Assume that the number of calls follows the Poisson distribution. -In a box of 16 chocolates,there are four chocolates with coconut filling.What is the probability of choosing four chocolates,none of which have coconut fillings?

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Develop a realistic example of a pair of random variables for which you would expect to find negative covariance.

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An important generalization of the Bernoulli distribution concerns the case where a random experiment with infinite outcomes is repeatedly independent.

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THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING: Consider the following probability distribution function. THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING: Consider the following probability distribution function.    -What is P(X ≥ 2)? -What is P(X ≥ 2)?

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Let the random variable Y = a + bX.Then σY = Let the random variable Y = a + bX.Then σ<sub>Y</sub> =    σX σX

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THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING: The number of people arriving at a bicycle repair shop follows a Poisson distribution with an average of 5 arrivals per hour.Let X represent the number of people arriving per hour. -What is the probability that seven people arrive at the bike repair shop in a one hour period of time?

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Which of the following is an example of a continuous random variable?

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THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING: The following table displays the joint probability distribution of two discrete random variables X and Y. THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING: The following table displays the joint probability distribution of two discrete random variables X and Y.   -Compute the variance for the linear function W = 2X + Y. -Compute the variance for the linear function W = 2X + Y.

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What is the probability that X is farther than one standard deviation from the mean?

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THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING: The probability that a person catches a cold during the cold and flu season is 0.4.Assume that 10 people are chosen at random. -What is the probability that four or more of them will catch a cold?

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