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 21 3 19 4 23 5 18 6 16 7 20 8 18 9 22 10 20 11 15 12 22 a)
Compute four-week and five-week moving averages for the time series.