12. value 6.66 points Problem 3-20 In this problem, you are to test the validity of your forecasting model. Here are the forecasts for a model you have been using and the actual demands that occurred: WEEK 1 2 3 4 5 6 FORECAST 750 795 895 895 945 920 ACTUAL 845 945 995 845 845 990 a. Use the method stated in the text to compute the MAD and tracking signal for each week. (Negative values should be indicated by a minus sign. Round your "Tracking Signal" to 1 decimal place and all other answers to the nearest whole number.) Absolute Deviation Sum of Absolute Deviation Deviation RSFE MAD TS Week Forecast 1 750 2 795 3 895 4 895 Actual 845 945 995 845 5 945 845 990 6 920 b. Decide whether the forecasting model you have been using is giving reasonable results. The forecasting model is acceptable The forecasting model is unacceptable