A plot in the article “Thermal Conductivity of Polyethylene:

The Effects of Crystal Size, Density, and Orientation on the Thermal Conductivity” (Polymer Engr. and Science, 1972:

204–208) suggests that the expected value of thermal conductivity y is a linear function of , where x is lamellar thickness.

x 240 410 460 490 520 590 745 8300 y 12.0 14.7 14.7 15.2 15.2 15.6 16.0 18.1

a. Estimate the parameters of the regression function and the regression function itself.

b. Predict the value of thermal conductivity when lamellar thickness is 500 Å.