9. A ski repair shop at a resort in Colorado sells replacement poles each season. The shop needs to develop a forecast of next seasons sales so that it can place an order for poles with its supplier well in advance of the beginning of the season. Sales data for the past five years are shown below.

Year	1	2	3	4	5
Sales (units)	375	395	360	400	380

Develop and compare the forecasts given by the following models:

a. A five-year moving average model.

b. A weighted moving average model with weights of 0.1, 0.1, 0.2, 0.3, and 0.3 for years 1 through 5, respectively.

c. An exponential smoothing model with a year 1 forecast of 380 and = 0.2.