A textbook publishing company has compiled data on total annual sales of its business texts for the preceding nine years: Click here for the Excel Data File a. Using an appropriate model, forecast textbook sales for each of the next five years. (Round your intermediate calculations 3 decimal places and final answers to 2 decimal places.) b. Compute +/2 s control limits for the control chart for forecast errors using just data from the original nine periods. (Round your intermediate calculations to 4 decimal places and final answer to 2 decimal places.) c. Suppose actual sales for the next five years turn out as follows: b. Compute +/2 s control limits for the control chart for forecast errors using just data from the original nine periods. (Round your intermediate calculations to 4 decimal places and final answer to 2 decimal places.) c. Suppose actual sales for the next five years turn out as follows: Is the forecast performing adequately? No Yes