18.12 Assume that your stock of sales merchandise is maintained based on the forecast demand. If the distributor's sales personnel call on the first day of each month, compute your forecast sales by each of the three methods requested here. Actual June 140 July 180 August 170 a. Using a simple three-month moving average, what is the forecast for September? b. Using a weighted moving average, what is the forecast for September with weights of o.20, 0.30, and 0.50 for June, July, and August, respectively? c. Using single exponential smoothing and assuming that the forecast for June had been 130, forecast sales for September with a smoothing constant alpha of 0.30. 18.21 The following table shows predicted product demand using your particular forecasting method along with the actual demand that occurred. (Answers in Appendix D Forecast Actual 1,500 1,400 1,550 1,500 1,700 1.600 15 1,750 1.650 1.800 1,700 a. Compute the MAD and Bias. b. Discuss whether your forecasting method is giving good predictions VE su to e noi