gasoline sales time series data in the given table. Week Sales (1,000s of gallons) 1 18 22 15 26 18 17 7 21 8 19 9 22 10 18 11 12 17 21 (a) Compute four-week and five-week moving averages for the time series. Do not round intermediate calculations. If required, round your answers to two decimal places. Week Sales 4-Week Moving 5-Week Average Moving Average 1 18 2 22 3 15 4 26 5 18 6 17 7 21 8 19 9 22 10 18 11 17 12 21 (b) Compute the MSE for the four-week and five-week moving average forecasts. Do not round intermediate calculations. If required, round your answers to two decimal places. MSE for four-week moving average- MSE for five-week moving average (c) What appears to be the best number of weeks of past data (three, four, or five) to use in the moving average computation? Consider that the MSE for the three-week moving average is 11.407. - Select your