Question: A local bank has recently installed an automatic teller machine
A local bank has recently installed an automatic teller machine (ATM). At a regional meeting, an ATM specialist tells the bank manager that usage times will be normally distributed and the variability in the amount of time customers require to use the machine will start out relatively high, then eventually settle down to a standard deviation of 0.8 minutes. The manager, skeptical that the variability could be this great, has a study done in which a random sample of 30 persons is timed while using the machine. Analysis of the data shows a standard deviation of 0.61 minutes. At the 0.05 level, test whether the standard deviation of usage times for this bank’s customers might actually be less than the amount predicted at the regional meeting.
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