Refer to the gasoline sales time series data in the given table.

Week	Sales (1000s of gallons)
1	18
2	20
3	18
4	23
5	17
6	16
7	20
8	17
9	22
10	20
11	16
12	23

a. Compute four-week and five-week moving averages for the time series. Round your answers to two decimal places. 4-Week 5-Week Week Sales Moving Average | Moving Average 1 18 2 20 3 18 4 23 5 17 20.50 X 6 16 20.25 X 19.80 X 20 18.75 X 19.20 X 8 17 19.00 V 19.00 X 9 22 17.25 X 18.60 10 20 18.50 X 18.20 X 11 16 19.75 V 18.80 X 12 23 18.75 V 19.00 b. Compute the MSE for the four-week and five-week moving average forecasts. Round your intermediate calculations and final answers to two decimal places. MSE for four-week moving average = 12.79 X MSE for five-week moving average = 9.47 X 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 MSE for the three-week moving average is 9.88. Three X