A study was done to determine the effects of two factors on the latherability of soap. The two factors were type of water (tap or distilled) and glycerol (present or absent). The outcome measured was the amount of foam produced (in milliliters). The experiment was repeated three times for each combination of the factors. The results are as follows.

a. Can you reject the hypothesis of no interactions? Explain.

b. Can the main effect of water type on the amount of foam be interpreted? If so, interpret the main effect, using the α = 0.01 level of significance. If not, explain why not.

c. Can the main effect of glycerol on the amount of foam be interpreted? If so, interpret the main effect, using the α = 0.01 level of significance. If not, explain why not.

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Distilled Water Tap Water No Glycerol 165 181 168 155 142 139 Glycerol 170 197 190 139 160 160