a. Problem 2 (15pt) DigiSonic observes from the sales data that sales of Blu-Ray discs have been decreasing over the last year. As mentioned earlier, this is due to the increasing popularity of online movie platforms among customers. DigiSonic wants to incorporate this decreasing trend into its forecasts. You have learned that the double exponential smoothing method accounts for such trends in the data. Use the double (trend-adjusted) exponential smoothing method to forecast sales for months 2 to 13 (i.e., F2 to F13), assuming S1=1376 and T1=-25 and set a=0.8 and B=0.2. (10pt) b. Create a plot showing the actual sales, the double exponential smoothing forecast, and the forecast obtained using simple exponential smoothing in Problem 2 with a=0.8 for months 1 to 12 on the same graph. (3pt) c. Compute MAD and MAPE for months 2 through 12 for the double exponential smoothing forecast and compare them with those of simple exponential smoothing in problem 2(c). Based on your calculations, is single or double exponential smoothing a better approach in this specific case? Why? (3pt) d. Develop a simple linear regression model using month as the independent variable to forecast the DigiSonic's Blu-Ray disc sales for month 13 (i.e., F13). Compare this forecast to the forecast obtained in part (a) for sales in month 13. Based on this, explain the difference between the two methods (regression, double exponential smoothing). (9pt)