A textbook publishing company has compiled data on total annual sales of its business textbooks for the preceding eight years: \& a. Plot the data and fit an appropriate model to it. Forecast the preceding eight years, and determine the forecast errors. Finally, construct a 2s control chart. b. Using the model, forecast textbook sales for each of the next five years. c. Suppose actual sales for the next five years turn out as follows: Calculate the forecast errors for Years 9 to 13. Is the forecasting process in control? Explain