Following are data on maximum ice thickness in millimeters (y). average number of days per year of ice cover (xi). average number of days the bottom temperature is lower than 8°C (x2), and the average snow depth in millimeters (x3) for 13 lakes in Minnesota.

b. Predict the ice thickness for a lake which is covered by ice an average of 140 days per year. the bottom temperature is less than 8°C an average of 190 days per year, and the average snow depth is 60 millimeters.
c. Refer to part (b). Construct a 95% confidence interval for the ice thickness.
d. Refer to part (b). Construct a 95% prediction interval for the ice thickness.
e. What percentage of the variation in ice thickness is explained by the model?
f. Is the model useful for prediction? Why or why not? Use the a = 0.05 level.
g. Test Ho: = 0 versus H1: β1* 0 at the a = 0.05 level. Can you reject Ho? Repeat for β2 and β3.

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