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A study of long distance phone calls made from the corporate offices of the Pepsi Bottling Group, Inc., in Somers, New York, showed the calls follow the normal distribution. The mean length of time per call was 4.2 minutes and the standard deviation was 0.60 minutes. a. What fraction of the calls last between 4.2 and 5 minutes?
b. What fraction of the calls last more than 5 minutes?
c. What fraction of the calls last between 5 and 6 minutes?
d. What fraction of the calls last between 4 and 6 minutes?
e. As part of her report to the president, the Director of Communications would like to reportthe length of the longest (in duration) 4 percent of the calls. What is this time?

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Solution Summary

This solution provides a detailed step by step explanation of the given statistics problem regarding normal distribution and the fraction of calls that last several different lengths of time.

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Let X represent the length of the phone call. From the condition, the mean of X is E(X) = 4.2 and its standard deviation is 0.6. Let Y = (X-4.2)/0.6, then Y ...

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