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Problem 15-07

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

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. Round your answers to two decimal places.

Week	Sales	4-Week Moving Average	5-Week Moving Average
1	17
2	21
3	19
4	23
5	18	fill in the blank 1
6	16	fill in the blank 2	fill in the blank 3
7	20	fill in the blank 4	fill in the blank 5
8	18	fill in the blank 6	fill in the blank 7
9	22	fill in the blank 8	fill in the blank 9
10	20	fill in the blank 10	fill in the blank 11
11	15	fill in the blank 12	fill in the blank 13
12	22	fill in the blank 14	fill in the blank 15

2. Compute the MSE for the four-week and five-week moving average forecasts. Round your intermediate calculations to two decimal places and round your final answers to two decimal places. MSE for four-week moving average = fill in the blank 16 MSE for five-week moving average = fill in the blank 17
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 10.22.