Suppose these data show the number of gallons of gasoline sold by a gasoline distributor in Bennington, Vermont, over the past 12 weeks.
Week Sales (1,000s of gallons)
1 17
2 22
3 20
4 24
5 18
6 17
7 21
8 19
9 23
10 21
11 16
12 23
(a) Using a weight of
1
2
for the most recent observation,
1
3
for the second most recent observation, and
1
6
for third most recent observation, compute a three-week weighted moving average for the time series. (Round your answers to two decimal places.)

Compute four-week and five-week moving averages for the time series.
Week Time Series Moving
Value Average Forecast

1 17
2 22
3 20
4 24
5 18
6 17
7 21
8 19
9 23
10 21
11 16
12 23
(b) Compute the MSE for the four-week moving average forecasts. (Round your answer to two decimal places.)
Compute the MSE for the five-week moving average forecasts. (Round your answer to two decimal places.)
(c) What appears to be the best number of weeks of past data (three, four, or five) to use in the moving average computation? MSE for the three-week moving average is 11.12.