Weekly sales of the Weber food processor for the past 10 weeks have been as follows (Chapter 15): Week Sales Week Sales 1 980 6 990 2 1040 7 1030 3 1120 8 1260 4 1050 9 1240 5 960 10 1100 a. Determine, on the basis of minimizing the mean square error, whether a three- or four-period simple moving average model gives a better forecast for this problem. b. For each model, forecast sales for Week 11.