2. The last four weekly values of sales were 80, 100, 105, and 90 units. The last four forecasts (for the same four weeks) were 60, 80, 95, and 75 units. Calculate MAD, MSE, and MAPE for these four weeks. (12 marks) Sales Forecast Error Error squared Pct. error 80 60 20 400 25 100 80 20 400 .20 105 95 10 100 095 90 75 15 225 167