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Using the Graphing Calculator

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2.5 Measures of Variability: Range, Standard Deviation, and Variance

A branch of a local bank decides to try two different approaches to manage their lines of customers.  During one Friday, the branch uses only one line.  As one of the four tellers become free, customers move into the open window position.  On another Friday, customers choose any of four lines with a teller at each end.  A sample of some of the waiting times in minutes is included below for each of the two line strategies.  Calculate the mean and the standard deviation for each strategy and compare them.  What do you notice?

Single Line:                 6.5, 6.6, 6.7, 6.8, 7.1, 7.3, 7.4, 7.7, 7.7, 7.7

Multiple Lines:          4.2, 5.4, 5.8, 6.2, 6.7, 7.7, 7.7, 8.5, 9.3, 10.0


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