Concept explainers
Suppose that the length of long distance phone calls, measured in minutes, Is known to have an exponential distribution with the average length of a call equal to eight minutes.
a. Define the random variable. X= _______________
b. Is X continuous or discrete?
c. X~____
d.
e.
f. Draw a graph of the
g. Find the probability that a phone call lasts less than nine minutes.
h. Find the probability that a phone call lasts more than nine minutes.
i. Find the probability that a phone call lasts between seven and nine minutes.
j. if 25 phone calls are made one after another, on average, what would you expect the total to be? Why?
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