data collected on the gasoline sales over the

Question

Data collected on the gasoline sales over the past 12 weeks are shown in the following 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

a) Using a weight of 1/2 for the most recent observation, 1/3 for the second most recent,and 1⁄6 for third most recent, compute a three-week weighted moving average for the time series. Compute the MAD, MSE and MPE for this method.

b) Use exponential smoothing with a smoothing constant of 0.1 to forecast the gasoline sales . Assume that last period's forecast for year 1 is 15,000 gallons to begin the procedure. Which method do you think is best?. Is this an improvement over the weighted average- use all measures above i.e MAD,MSE, MAPE

c) Use regression analysis to estimate the line of best fit -use the manual method with the formulas shown below.

y=a+bx

where:

 b= n∑xy-∑x∑y

       n∑x² -(∑X)²

a=y-bx