15) After graduation, you take a position at Top-Slice, a well-known manufacturer of golf balls. One of the duties is to forecast monthly demand for golf balls. Using the following data, you developed a regression model that expresses monthly sales as a function of average temperature for the month: Monthly sales -767.7 +98.5 (average temperature) March 2017 April May June July August September October November December January 2018 February MONTHLY SALES 4670 5310 6320 7080 7210 7040 6590 5520 4640 4000 2840 3170 AVERAGE TEMPERATURE 52 58 69 75 83 82 78 65 54 48 41 42 a) Using Equations (9.8) and (9.9) from the text, show how the a and b values of -767.7 and 98.5 were calculated. b) Use the regression forecasting model to forecast total golf ball sales for June and July 2018. Average temperatures are expected to be 76 degrees in June and 82 degrees in July. c) Is this regression model a time series or a causal forecasting model? Explain.
