3. Residential mailboxes in Des Moines, Iowa, should be installed such that the bottom of the mailbox is 42 inches above the ground. This rule is designed for safety and to accommodate short mail carriers. A random sample of 75 mailboxes in a large city was selected. The height of each was carefully measured, and the sample mean was 43.22 inches. Assume 0:7.6 inches. At a signicance level of 0.05, is there any evidence to suggest the true mean height of mailboxes in Des Moines is different from 42 inches? (a) Formulate the null and alternative hypotheses. (b) Compute the appropriate test statistic. (0) Produce a sketch of the rejection region(s) with the critical value(s) labelled. (d) Compute the P-value. (e) State your conclusion (reject or fail to reject the null hypothesis). (f) Interpret your conclusion in context