[21/04, 7:23 pm] Faisal Al Ghanami : 1a. Three-period Moving Average forecast for periods 13-15: Period 13 = (248+370+424)/3 = 347.33 Period 14 = (370+424+286)/3 = 360 Period 15 = (424+286+444)/3 = 384.67 1b. Two-Period Weighted Moving Average forecast for periods 12-15 (weights 0.7 and 0.3): Period 12 = (370*0.7) + (248*0.3) = 333.4 Period 13 = (424*0.7) + (370*0.3) = 407.8 Period 14 = (286*0.7) + (424*0.3) = 327.4 Period 15 = (444*0.7) + (286*0.3) = 396.6 [21/04, 7:23 pm] Faisal Al Ghanami : 1c. Exponential Smoothing forecast with alpha = 0.25 for Periods 11-15 Period 11 = 0.25*248 + 0.75*252 = 251 Period 12 = 0.25*370 + 0.75*251 = 280.75 Period 13 = 0.25*424 + 0.75*280.75 = 316.56 Period 14 = 0.25*286 + 0.75*316.56 = 308.92 Period 15 = 0.25*444 + 0.75*308.92 = 342.69 [21/04, 7:23 pm] Faisal Al Ghanami : 1d. Forecast Error = Actual - Forecast MAD = SUM[|Forecast Error| / n = [|248-251| + [|370-280.75| + [|424-316.56| + [|286-308.92| + [|444-342.69|] / 5 = 770.58/5 = 154.12