A textbook publishing company has compiled data on total annual sales of its business texts for the preceding nine years:

Year 1 2 3 4 5 6 7 8 9 Sales (000) 40.2 44.5 48.0 52.3 55.8 57.1 62.4 69.0 73.7

a. Using an appropriate model, forecast textbook sales for each of the next five years.

b. Prepare a control chart for the forecast errors using the original data. Use 2s limits.

c. Suppose actual sales for the next five years turn out as follows:

Year 10 11 12 13 14 Sales (000) 77.2 82.1 87.8 90.6 98.9 Is the forecast performing adequately? Explain.

 LO.1