The following partial Excel add- in ( MegaStat) regression output for the service time data relates to predicting service times for 1, 2, 3, 4, 5, 6, and 7 copiers.

a. Report (as shown on the computer output) a point estimate of and a 95 percent confidence interval for the mean time to service four copiers.
b. Report (as shown on the computer output) a point prediction of and a 95 percent prediction interval for the time to service four copiers on a single call.
c. For this case: n = 11, b0 = 11.4641, b1 = 24.6022, and s 4.615. Using this information and a distance value (called Leverage on the add-in output), hand calculate (within rounding) the confidence interval of part a and the prediction interval of part b.
d. If we examine the service time data, we see that there was at least one call on which Accu-Copiers serviced each of 1, 2, 3, 4, 5, 6, and 7 copiers. The 95 percent confidence intervals for the mean service times on these calls might be used to schedule future service calls. To understand this, note that a person making service calls will (in, say, a year or more) make a very large number of service calls. Some of the person€™s individual service times will be below, and some will be above, the corresponding mean service times. However, because the very large number of individual service times will average out to the mean service times, it seems fair to both the efficiency of the company and to the person making service calls to schedule service calls by using estimates of the mean service times. Therefore, suppose we wish to schedule a call to service five copiers. Examining the computer output, we see that a 95 percent confidence interval for the mean time to service five copiers is [130.753, 138.197]. Because the mean time might be 138.197 minutes, it would seem fair to allow 138 minutes to make the service call. Now suppose we wish to schedule a call to service four copiers. Determine how many minutes to allow for the service call.

Predicted values for: Minutes (y) 95% Confidence Intervals wer upper 42.226 65.357 81.715 88.827 106.721 113.025 130.753 38.197 154.139 164.016 177.233 190.126 95% Prediction Intervals lower 23.944 49.224 74.241 98.967 123.391 147.528 171.410 Coplers (x) Predicted 36.066 60.669 85.271 109.873 134.475 159.077 183.680 upper 48.188 72.113 96.300 120.779 145.559 170.627 195.950 Leverage 0.348 0.202 0.116 0.091 0.127 0.224 0.381 29.907 55.980 4