In his book, D.C. Montgomery presents the results of an experiment involving a storage battery used in the launching mechanism of a shoulder-fired ground-to-air missile. Three material types can be used to make the battery plates. The objective is to design a battery that is relatively unaffected by the ambient temperature. The output response from the battery is effective life in hours. Three temperature levels are selected, and a factorial experiment with four replicates is run. The data are as follows:

a. Test the above hypotheses and draw conclusions using the analysis of variance with α = 0.05.

b. Analyze the residuals from this experiment.

c. Graphically analyze any interaction.

Temperature (F) Material Low Medium High 130 155 34 40 20 70 1 74 180 80 75 82 58 150 188 136 122 25 70 159 126 106 115 58 45 138 110 174 120 96 104 3 168 160 150 139 82 60 2.