The manager of a local fast-food restaurant is interested in improving the service provided to customers who use the restaurant's drive-up window. As a first step in this process, the manager asks his assistant to record the time (in minutes) it takes to serve 200 different customers at the final window in the facility's drive-up system. The given 200 customer service times are all observed during the busiest hour of the day for this fast-food operation. a. Calculate a point estimate of the population mean from the sample selected above.
What is the sampling error, that is, by how much does the sample mean differ from the population mean?
b. Calculate a good approximation for the standard error of the mean.
c. If you wanted to halve the standard error from part c, what approximate sample size would you need?