12.49 Variability and F Refer to the previous two exercises.

a. In the ANOVA table, show how the Total SS breaks into two parts and explain what each part represents.

b. From the ANOVA table, explain why the overall sample standard deviation of y values is sy = 2192787>56 = 58.7. Explain the difference between the interpretation of this standard deviation and the residual standard deviation s of 36.1.

c. Exercise 12.15 reported a t statistic of 9.64 for testing independence of these variables. Report the F test statistic from the table here and explain how it relates to that t statistic.