The spreadsheet below shows results for several forecasting methods applied to the data for January through August shown in Column B of the spreadsheet, and the MAD for each forecasting method. (Note, columns D, F, and H are hidden in the spreadsheet below.)

The forecasts in column C were obtained using a 3-step moving average model; the forecasts in column E were obtained using a 4-step weighted moving average model with weights w₁ = 0.4, w₂ = 0.35, w₃ = 0.2, and w₄ = 0.05; and the forecasts in column E were obtained using an exponential smoothing model with = 0.7. All answers must be based on the Excel output below where possible.

a) Specify the Excel formula used to calculate the number in cell E-10. Be specific exactly what would you type in that cell to do the computation?

b) In calculating the exponentially smoothed forecasts in column G using Excel, what is the damping factor?

c) Based on the calculation of the Mean Absolute Deviation shown, which model provides the best forecast for September?d) The actual demand for September, when it occurs, is 60. Briefly comment on what this tells you and how you would proceed in making decisions that depend on being able to forecast this demand for the future.

C E G 1 Month Demand MA; Forecast WMA, Forecast | Expon Smooth Forecast a=0.7 20 #N/A 36 42 3 Jan 4 Feb 5 Mar 6 Apr 7 May 8 Jun 18 #N/A #N/A 32.67 32.00 33.33 27.33 37.33 37.33 31.20 38.76 24.23 40 30.1 32.5 24 48 40 10 Aug 11 Sep 29.3 36.5 39.6 35.27 27.38 41.81 40.54 bo o no 11.07 13 14 MAD 15 16 10.15 13.86 17