Consider the regression model fit to the coal and limestone mixture data in Exercise 12-17. Use density as the response.

(a) Calculate 90% confidence intervals on each regression coefficient.

(b) Calculate a 90% confidence interval on mean density when the dielectric constant = 2.3 and the loss factor = 0.025.

(c) Calculate a prediction interval on density for the same values of the regressors used in part (b).

Density Dielectric Constant Loss Factor 0.016 0.749 2.05 0.798 2.15 0.02 0.849 2.25 0.022 0.023 0.877 2.3 0.026 0.929 2.4 0.963 2.47 0.028 0.997 2.54 0.031 0.034 1.046 2.64 1.133 2.85 0.039 1.17 2.94 0.042 3.05 1.215 0.045