Suppose average pizza delivery times are normally distributed with an unknown population mean and a population standard deviation of six minutes. A random sample of 28 pizza delivery restaurants is taken and has a sample mean delivery time of 36 minutes. In words, define the random variable X : O X is the time it take the pizza to be delivered. O X is the mean time it it took a sample of 28 pizza delivery restaurants to deliver a pizza.Suppose we have data from a sample. The sample mean is 15, and the error bound for the mean is 3.2. What is the confidence interval estimate for the population mean