4.7. refer to copier maintenance problem 1.20. a. estimate the expected number of minutes spent when there are 3, 5, and 7 copiers to be serviced, respectively. use interval estimates with a 90 percent family confidence coefficient based on the working-hoteiiing procedure. b. two service calls for preventive maintenance are scheduled in which the numbers of copiers to be serviced are 4 and 7, respectively. a family of prediction intervals for the times to be spent on these calls is desired with a 90 percent family confidence coefficient. which procedure, scheffe or bonferroni, will provide tighter prediction limits here? c. obtain the family of prediction intervals required in part (b), using the more efficient procedure.