Customer orders placed online at an e-retailer are filled and shipped from four different warehouses in Cleveland, Atlanta, Denver, and Sacramento. A random sample of 20 customer orders was chosen from all shipments filled in a week at the four warehouses and weighed. The weights of each sampled shipment (in ounces) are contained in the file Shipments.
a. Based on the sampled shipments, can you conclude that the average weights of shipped customer orders are different at the four warehouses? Use an alpha of 0.05 to conduct the appropriate test analysis.

b. If a difference is found in the average weights of customer orders, conduct a post-test analysis to determine where the difference exists. Use an alpha of 0.05 to perform the comparison.