You are the manager of a restaurant that delivers pizza to university residences. You have changed your delivery process to reduce the average time between the order and completion of delivery from the current 25 minutes. For a one mark bonus, write the name of your favourite city at the top of this page. A sample of 36 orders using the new delivery process yields a sample mean of 22.4 minutes and a sample standard deviation of 6 minutes.

calculate a 95% confidence interval for mean pizza delivery times