In: Math
Refer to the gasoline sales time series data in the given table.
| Week | Sales (1,000s of gallons) | 
| 1 | 18 | 
| 2 | 22 | 
| 3 | 15 | 
| 4 | 24 | 
| 5 | 18 | 
| 6 | 15 | 
| 7 | 21 | 
| 8 | 19 | 
| 9 | 21 | 
| 10 | 20 | 
| 11 | 16 | 
| 12 | 22 | 
| Compute four-week and five-week moving averages for the time series. | |||||||||||||||||||||||||||||||||||||||||||||||||||||
| If required, round your answers to two decimal places. | |||||||||||||||||||||||||||||||||||||||||||||||||||||
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a) solution of this part is in the adjoining pictures



b)
MSE for four-week moving average is 8.905
MSE for five-week moving average is 4.232
c)
since the five week moving average has smaller MSE = 4.232
hence it is the best number of past data to use in the moving average computation.