HW2

Prof. Shihao Yang (shihao.yang@isye.gatech.edu) ISyE 4031 Regression and Forecasting HW #2 Problem 1 Accu-Copiers, Inc., sells and services the Accu-500 copying machine. As part of its standard service contract, the company agrees to perform routine services on this copier. To obtain information about the time it takes to perform routine service, the company has collected data for 11 service calls. (.xls file is also provided) Service Call Number of Copiers Serviced (x) Number of Minutes Required(y) 1 4 109 2 2 58 3 5 138 4 7 189 5 1 37 6 3 82 7 4 103 8 5 134 9 2 68 10 4 112 11 6 154 a) Use the software of your choice (R, Minitab, ...) to show the scatter plot of x and y. b) Based on the scatter plot, discuss why the simple linear regression model might be a good fit. c) Calculate the regression line coefficients using the formulas. (include all the steps) d) Use the software and fit the regression line. Also provide the plot. e) Interpret the meaning of the slope ࠵? 1 f) Interpret the meaning of the y-intercept ࠵? 0 g) If they want to service 10 copiers what is your expectation about the required time. h) Find an estimation for the variability of the model. Problem 2 An accountant wishes to predict direct labor cost (y) on the basis of the batch size (x) of a product produced in a job shop. Data for 12 runs are given. (.xls file is also provided) Directed Labor Cost (y) Batch Size (x) 71 5 663 62 381 35 138 12 861 83 145 14 493 46