Using the following ANOVA table based on data in Problem 6 of Chapter 8 about the regression relationship of respiratory cancer mortality rates (Y) to air pollution index (X1), mean age (X2), and percentage of workforce employed in a certain industry (X3), test the following hypotheses:
a. H0: pYX2|X1 = 0
b. H0: PYX3|X1,X2 = 0

c. H0: “The addition of X2 and X3 to a model already containing X1 does not significantly improve the prediction of Y.”
d. Based on these results, which variables are important predictors of Y? Use α = .05.
e. State the results in part (a) in terms of equivalent tests about population semipartial correlations.