11.39 A regression model is desired relating temperature and the proportion of impurities passing through solid helium. Temperature is listed in degrees centigrade.

The data are as follows:

Temperature (◦C) Proportion of Impurities

−260.5 0.425

−255.7 0.224

−264.6 0.453

−265.0 0.475

−270.0 0.705

−272.0 0.860

−272.5 0.935

−272.6 0.961

−272.8 0.979

−272.9 0.990

(a) Fit a linear regression model.

(b) Does it appear that the proportion of impurities passing through helium increases as the temperature approaches −273 degrees centigrade?

(c) Find R2 .

(d) Based on the information above, does the linear model seem appropriate? What additional information would you need to better answer that question?