The monthly sales levels (measures in thousands of Saudi riyals) for a leading Saudi company are shown in the following table. Plot the monthly sales data using minitab and the demonstrate the following: a) Smooth the data and forecast Jan 2019 sales level using simple exponential smoothing with a smoothing constant of 0.5 and initial smoothed value of 16.8. Plot and show the fits, residuals and forecast in a table. b) Smooth the data and forecast Jan 2019 sales level using Holt's linear smoothing with all smoothing constants equal to 0.5 and initial smoothed value of 16.8. Plot and show the fits, residuals and forecast in a table. c) Smooth the data and forecast Jan 2019 sales level using Winters multiplicative smoothing with all smoothing constants equal to 0.5 and initial smoothed value of 16.8. Plot and show the fits, residuals and forecast in a table. d) Compare and evaluate the previous exponential smoothing methods in parts (a), (b) and (c) using MAPE, MAD and MSE, and explain your preferred method for these date. Show your comparison in a table. Year Month Sales Jan 16.8 Feb 12.7 Mar 26.9 Apr 61.4 May 147.8 Jun 57.9 Jul 51.3 Aug 53.5 Sep 23.0 Oct 41.3 Nor 19.3 Dec 22.7 2016 Year Month Sales Year Month Sales Jan 15.3 27.7 Feb 30.8 36.3 Mar 25.5 51.1 Apr 217.5 May Jun 2017 Jul Aug Sep Oct Nov Dec 103.1 197.6 68.6 39.9 91.3 58.7 59.6 33.4 53.7 2018 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 206.2 110.0 102.8 128.8 104.7 111.0 63.7 82.6