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 a temperature with a standard deviation of 2 degrees Fahrenheit. The desired range is 18 to 30 degrees Fahrenheit. Find the C_pkcapability indexes.