Referring to Exercise 12.12, we have added one more predictor x3 = skull width (cm). The output for a regression analysis is shown in Table 11.

(a) Test H0 : β3 = 0 versus H0 : β3 # 0 with a = .05.
(b) Test H0: β2 = 0 versus H0: β2 ‰  0 with a = .05.
(c) Estimate the expected value of weight (Y) corresponding to x1 = 150, x2 = 250, and x3 = 25.
(d) What is the proportion of y variability explained by the regression on x1, x2, and x3?

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The regreasion equation io y15815.89 x1+3.19 x228.2x3 Predictor Constant x2 x2 x3 Coef SE Coe t 15807275.7 5.73 4.38 3.33 0.000 0,000 0.003 28 24 11.00 2.57 0.016 5.886 3.1903 1.343 0.9568 S-46.8673 R-Sq-88.4 Analyois of Variance Source Regresaion Residual Brror Total DF SB MS 3 434979144993 66.01 0.000 2197 26 29 57110 492089