Refrigerator manufacturers design their freezer units to maintain temperatures within a certain range. Too much temperature variation can result in food spoiling due to thawing. Too little temperature variation can cause higher energy costs as the refrigerator’s compressor cycles on and off more often than necessary. Suppose Amana, a major refrigerator manufacturer, wants the freezer of a particular model to have a standard deviation equal to 4°F. To test for this variation under normal operating conditions, the freezer was filled to 75% capacity with food and was opened periodically during an 8 hour day for 10 seconds’ duration. The following table shows the freezer temperature readings in degrees Fahrenheit that were recorded during this experiment. These data can also be found in the Excel file freezer temperatures.xlsx.
a. Using α = 0.05, test to determine if Amana has achieved its goal.
b. Verify your results using PHStat.
c. Interpret the p value obtained from the software.

  • CreatedJuly 28, 2015
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