This week you will use an excel spreadsheet to analyze forecasting performance. Your company produces and distributes two lines of Consumer External Hard Drives: 1 Terabyte drives (1 Tb) and 5 Terabyte Drives (5 Tb). The unit sales levels and forecasts for the last two previous years are in the table below. For this exercise, You have been asked to calculate the Forecast error, Forecast Percentage, Mean percentage Error (MPE) and Mean Absolute Percentage Error (MAPE) for (a) each type of terabyte (b) each year, and (c) for each two-year period