Chapter 4: Q62E (page 246)
Assume that X is a random variable having a Poisson probability distribution with a mean of 1.5. Use statistical software to find the following probabilities:
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Chapter 4: Q62E (page 246)
Assume that X is a random variable having a Poisson probability distribution with a mean of 1.5. Use statistical software to find the following probabilities:
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Suppose is a normally distributed random variable with and . Find a value of the random variable, call it , such that
a)
b)
c)
d)
e) 10% of the values of role="math" localid="1652160513072" are less thanrole="math" localid="1652160519976"
f)1% of the values of are greater than
Identify the type of continuous random variable鈥攗niform,normal, or exponential鈥攄escribed by each of the following probability density functions:
a.
b.
c.
Public transit deaths. Millions of suburban commuters use the public transit system (e.g., subway trains) as an alter native to the automobile. While generally perceived as a safe mode of transportation, the average number of deaths per week due to public transit accidents is 5 (Bureau of Transportation Statistics, 2015).
a. Construct arguments both for and against the use of the Poisson distribution to characterize the number of deaths per week due to public transit accidents.
b. For the remainder of this exercise, assume the Poisson distribution is an adequate approximation for x, the number of deaths per week due to public transit accidents. Find and the standard deviation of x.
c. Based strictly on your answers to part b, is it likely that more than 12 deaths occur next week? Explain.
d. Find. Is this probability consistent with your answer to part c? Explain.
Elevator passenger arrivals. A study of the arrival process of people using elevators at a multilevel office building was conducted and the results reported in Building Services Engineering Research and Technology (October 2012). Suppose that at one particular time of day, elevator passengers arrive in batches of size 1 or 2 (i.e., either 1 or 2 people arrive at the same time to use the elevator). The researchers assumed that the number of batches, n, arriving over a specific time period follows a Poisson process with mean . Now let xn represent the number of passengers (either 1 or 2) in batch n and assume the batch size has probabilities . Then, the total number of passengers arriving over a specific time period is . The researchers showed that if are independent and identically distributed random variables and also independent of n, then y follows a compound Poisson distribution.
a. Find , i.e., the probability of no arrivals during the time period. [Hint: y = 0 only when n = 0.]
b. Find , i.e., the probability of only 1 arrival during the time period. [Hint: y = 1 only when n = 1 and .]
Hotels鈥 use of ecolabels. Refer to the Journal of Vacation Marketing (January 2016) study of travelers鈥 familiarity with ecolabels used by hotels, Exercise 2.64 (p. 104). Recall that adult travelers were shown a list of 6 different ecolabels, and asked, 鈥淪uppose the response is measured on a continuous scale from 10 (not familiar at all) to 50 (very familiar).鈥 The mean and standard deviation for the Energy Star ecolabel are 44 and 1.5, respectively. Assume the distribution of the responses is approximately normally distributed.
a. Find the probability that a response to Energy Star exceeds 43.
b. Find the probability that a response to Energy Star falls between 42 and 45.
c. If you observe a response of 35 to an ecolabel, do you think it is likely that the ecolabel was Energy Star? Explain.
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