Refer to the gasoline sales time series data below.

Gasoline Sales Time Series

Week Sales (1000s of gallons)

1 17

2 21

3 19

4 23

5 18

6 16

7 20

8 18

9 22

10 20

11 15

12 22

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

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

3. What appears to be the best number of weeks of past data (three, four, or five) to use in the moving average computation?