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In Gallup's Annual Consumption Habits Poll, telephone interviews were
conducted for a random sample of 1014 adults aged 18 and over. One of
the questions was, "How many cups of coffee, if any, do you drink on an
average day?" The following table shows the results obtained (Gallup website, August 6, 2012).
Number of Cups per day | Number of responses |
0 1 2 3 4 or more |
365 264 193 91 101 |
Define a random variable x = number of cups of coffee consumed on an
average day. Let x= 4 represent four or more cups.
a. Develop a probability distribution for x.
b. Compute the
c. Compute the variance of X.
d. Suppose we are only interested in adults who drink at least one
cup of coffee on an average day. For this group, let y = the number
of cups of coffee consumed on an average day. Compute the
expected value of y and compare it to the expected value of x.
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