(Solved): *4.7. Refer to Copier maintenance Problem 1.20. a. Estimate the expected number of minutes spent w ...

*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-Hotelling 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, Scheffé or Bonferroni, will provide tighter prediction limits here? c. Obtain the family of prediction intervals required in part (b), using the more efficient procedure. *1.20. Copier maintenance. The Tri-City Office Equipment Corporation sells an imported copier on a franchise basis and performs preventive maintenance and repair service on this copier. The data below have been collected from 45 recent calls on users to perform routine preventive maintenance service; for each call, $X$ is the number of copiers serviced and $Y$ is the total number of minutes spent by the service person. Assume that first-order regression model (1.1) is appropriate.