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

Week	Sales (1,000s of gallons)
1	18
2	22
3	15
4	24
5	18
6	15
7	21
8	19
9	21
10	20
11	16
12	22

(a)

Compute four-week and five-week moving averages for the time series.

If required, round your answers to two decimal places.

Week	Sales	4 Period Moving Average	5 period Moving Average
1	18
2	22
3	15
4	24
5	18
6	15
7	21
8	19
9	21
10	20
11	16
12	22

(b)

Compute the MSE for the four-week and five-week moving average forecasts.

If required, round your final answers to three 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 10.086.

- Select your answer -ThreeFourFiveItem 18