Ch08_Sect03_Keller MS_AISE TB

# Ch08_Sect03_Keller MS_AISE TB - CHAPTER 8 SECTION 3...

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Unformatted text preview: CHAPTER 8 SECTION 3: CONTINUOUS PROBABILITY DISTRIBUTIONS MULTIPLE CHOICE 116. If the random variable X is exponentially distributed with parameter λ = 3, then the probability P ( X ≥ 2) equals: a. 0.3333 b. 0.5000 c. 0.6667 d. 0.0025 ANS: D PTS: 1 REF: SECTION 8.3 117. If the random variable X is exponentially distributed with parameter λ = 1.5, then the probability P (2 ≤ X ≤ 4), up to 4 decimal places, is a. 0.6667 b. 0.0473 c. 0.5000 d. 0.2500 ANS: B PTS: 1 REF: SECTION 8.3 118. If the random variable X is exponentially distributed with parameter λ = 4, then the probability P ( X ≤ 0.25), up to 4 decimal places, is a. 0.6321 b. 0.3679 c. 0.2500 d. None of these choices. ANS: A PTS: 1 REF: SECTION 8.3 119. The exponential density function f(x) : a. is bell-shaped. b. is symmetrical. c. approaches infinity as x approaches zero. d. approaches zero as x approaches infinity. ANS: D PTS: 1 REF: SECTION 8.3 120. If the random variable X is exponentially distributed, then the mean of X will be: a. greater than the median. b. less than the median. c. equal to the median. d. Cannot tell; the answer depends on what λ is. ANS: A PTS: 1 REF: SECTION 8.3 121. Which of the following is not true for an exponential distribution with parameter λ ? a. μ = 1/ λ b. σ = 1/ λ c. The Y-intercept of f(x) is λ . d. All of these choices are true. ANS: D PTS: 1 REF: SECTION 8.3 This edition is intended for use outside of the U.S. only, with content that may be different from the U.S. Edition. This may not be resold, copied, or distributed without the prior consent of the publisher. 122. If the mean of an exponential distribution is 2, then the value of the parameter λ is a. b. 2.0 c. 0.5 d. 1.0 ANS: C PTS: 1 REF: SECTION 8.3 123. If the parameter of an exponential distribution is 1, then which of the following is not true? a. The density function is e- x for x ≥ 0. b. The mean is equal to 1. c. The standard deviation and variance are both equal to 1. d. All of these choices are true. ANS: D PTS: 1 REF: SECTION 8.3 124. Which of the following can have an exponential distribution? a. Time between phone calls coming in to a technical support desk. b. Time until the first customer arrives at the bank in the morning. c. Lifetime of a new battery. d. All of these choices are true. ANS: D PTS: 1 REF: SECTION 8.3 TRUE/FALSE 125. In the exponential distribution, X takes on an infinite number of possible values in the given range. ANS: T PTS: 1 REF: SECTION 8.3 126. The mean and standard deviation of an exponential random variable are equal to each other. ANS: T PTS: 1 REF: SECTION 8.3 127. If the mean of an exponential distribution is 2, then the value of the parameter λ is 2.0....
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Ch08_Sect03_Keller MS_AISE TB - CHAPTER 8 SECTION 3...

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