The length of time to do a complete full service oil change at Speedy-Lube is normally distributed with a meanof 15.8 minutes and a standard deviationof 2.2 minutes.
What percentage of complete full service oil changes will take less than 10 minutes? If 1000 cars had a complete full service oil change, how many would you expect to be finished in more than 20 minutes?
This solution provides calculations in Excel for percentage of complete full service oil changes.