A sample of 25 deliveries from an automobile parts supplier

A sample of 25 deliveries from an automobile parts supplier was timed and recorded. The sample revealed a mean of 57.79 minutes and a standard deviation of 6.58 minutes. Delivery times are thought to be normally distributed. a. You will estimate a confidence interval. What is the random variable and how is it distribute? The format of your response should be something like x N (mu, sigma) depending on the variable, but using numbers. b. Estimate a 96% confidence interval for the mean delivery time of all automobile parts from this supplier. c. Interpret this confidence interval. d. Re-estimate the 96% confidence interval for the mean delivery time of all automobile parts from this supplier, assuming n = 100. e. How does A differ from C? Why? f. What size sample would be required to estimate the delivery time of all automobile parts within 2 minutes at the 96% level?