The residuals given by the service time prediction equation y-bar = 11.4641 + 24.6022x are listed in Table 13.7(a).

a. In this exercise we construct a normal plot of these residuals. To construct this plot, we must first arrange the residuals in order from smallest to largest. These ordered residuals are given in Table 13.7(b). Denoting the ith ordered residual as e(i) (i = 1, 2, . . . , 11), we next compute for each value of i the point z(i). These computations are summarized in Table 13.7(b). Show how z(4) = – .46 and z(10) = 1.05 have been obtained.

b. The ordered residuals (the e(i)’ s) are plotted against the z(i)’s in Figure 13.28(c). Does this figure indicate a violation of the normality assumption? Explain.