Week Sales (1000s of gallons) 12 1 18 2 24 3 24 4 22 10 5 18 67 6 21 7 23 8 18 9 20 10 22 11 21 12 22 13 19 14 19 15 18 16 19 17 20 18 23 19 18 20 18 21 21 22 23 23 17 24 19 25 3 21 a. Compute four-week and five-week moving averages for the time series. b. Compute the MAPE for the four-week and five-week moving average forecasts. c. What appears to be the best number of weeks of past data (three, four, or five) to use in the moving average computation? Recall that the MAPE for the three-week moving average is 10.09%. d. What would be the projections of the 26th week for the four and five-week moving averages?