Question 2. Alexander Enterprises manufactures plastic parts for the automotive industry. Download data on its sales [in thousands of dollars] for ENE, E11 through 2016, [14. You are to forecast sales for 201?, (11 through 2D1T. (14. a. Begin by preparing a time series plot of the data set. Does it appear from this plot that a iineartrend model will be appropriate? Explain. {Mach your graph to your answer.} is. Lise a hiyariate linear regression trend model to estimate this trend equation: SALES = a + bthME} Is the sign of b 1what you would expect? Is it signicantly different from zero? 1it'll'hat is the coefcient of determination for this model? Explain your answers. c. Based on this model, make a trend forecast of sales [SNESFI'] for the four quarters of 201?. d. The actual sales SALESA for the four nuarters are provided in the table. Calculate RMSE for this forecast model in the historical period (20 12, 012015. 04} as well as for the forecast horizon (201?. (112911 Gel}. Which of these measures accuracy and which measures t