Assume that your stock of sales merchandise is maintained based on the forecast demand. If the distributor’s sales personnel call on the first day of each month, compute your fore-cast sales by each of the three methods requested here.
Actual
June ............. 140
July ............. 180
August ............. 170

a. Using a simple three- month moving average, what is the forecast for September?
b. Using a weighted moving average, what is the forecast for September with weights of .20, .30, and .50 for June, July, and August, respectively?
c. Using single exponential smoothing and assuming that the forecast for June had been 130, forecast sales for September with a smoothing constant alpha of .30.