Using DemandData. Xlsx file on the course website, and using the "Moving averages of 13" method, i. E., MA (13), calculate the moving averages for periods 81 through 100. In particular, start with forecast for period 81 using data from the previous 13 periods, i. E., from periods 68 through 80. Continue this process till you generate forecast for period 100. Now calculate errors, the differences between your forecasts and the data. What is the Mean Absolute Deviation of these errors? Choose the closest numerical answer.