Suppose that the waiting time for a pizza to be ready at a local pizzeria has been found to be normally distributed with a mean of 20 minutes and a standard deviation of 8 minutes. Suppose that in an effort to provide better service to the customers, the manager has decided to provide discounts to those individuals whose waiting time exceeds a predetermined time. The manager decides that 10% of the customers should receive this discount. What is the number of minutes they need to wait to receive the discount