Suppose these data show the number of gallons of gasoline sold by a gasoline distributor in Bennington, Vermont, over the past 12 weeks. Week Sales (1,000s of gallons) 1 18 2 22 3 20 4 24 5 18 6 16 7 20 8 19 9 23 10 20 11 15 12 22 (a) Compute four-week and five-week moving averages for the time series. Week Time Series Value 4-Week Moving Average Forecast 5-Week Moving Average Forecast 1 18 2 22 3 20 4 24 5 18 6 16 7 20 8 19 9 23 10 20 11 15 12 22 (b) Compute the MSE for the four-week moving average forecasts. (Round your answer to two decimal places.) Compute the MSE for the five-week moving average forecasts. (Round your answer to two decimal places.) (c) What appears to be the best number of weeks of past data (three, four, or five) to use in the moving average computation