Copier maintenance. The Tri-City O'ice 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 rstorder regression model (1.1) is appropriate. i: 'I 3 . . . 43 44 4S 2 X,: 2 4 3 ... 2 4 5 Y,-: 20 60 46 ... 27 61 77 a. Obtain a 90 percent confidence interval for the mean service time on calls in which six copiers are serviced. Interpret your confidence interval.d. Determine the boundary values of the 90 percent confidence band for the regression line when Xh = 6. Is your confidence band wider at this point than the confidence interval in part (a)? Should it be