The temperature control unit on a commercial freezer in a 24-hour grocery store is set to maintain a mean temperature of 23 degrees Fahrenheit. The temperature varies because people are constantly opening the freezer door to remove items, but the thermostat is capable of maintaining temperature with a standard deviation of 2 degrees Fahrenheit. The desired range is 18 to 30 degrees Fahrenheit.
(a) Find the Cp and Cpk capability indexes.
(b) In words, how would you describe the process capability?
(c) If improvement is desired, what might be some obstacles to increasing the capability?