Question

II.19. Prediction? Use the regression equation in the previous exercise to predict the weight of the soap after 30 days. Why is it clear that your answer makes no sense? What’s wrong with using the regression line to predict weight after 30 days? (Hint: See page 345.)

TABLE II.3 Weight (grams) of a bar of soap used to shower
Day Weight Day Weight Day Weight
1 124 8 84 16 27
2 121 9 78 18 16
5 103 10 71 19 12
6 96 12 58 20 8
7 90 13 50 21 6
Source: Rex Boggs.