Problem 15-07 (Algorithmic)

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

Week	Sales (1000s of gallons)
1	18
2	21
3	18
4	23
5	18
6	16
7	20
8	17
9	22
10	20
11	14
12	23

1. Compute four-week and five-week moving averages for the time series. Round your answers to two decimal places.

   Week	Sales	4-Week Moving Average	5-Week Moving Average
   1	18
   2	21
   3	18
   4	23
   5	18
   6	16
   7	20
   8	17
   9	22
   10	20
   11	14
   12	23

2. 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 = MSE for five-week moving average =
3. 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 12.04.