This sheet presents the annual sale of desks at Ashley Santa Monica in the past 12 years
a) Make exponential smoothing forecasts with alpha = 0.2.
b) Make 3-period moving average forecasts starting from period 4.
c) Make a time series plot to show SALES, Exponential Smoothing, and Moving Average forecasts on the same line chart.
Historical sale in the past 12 years
Year	Sales
1	978
2	1078
3	1170
4	1030
5	1176
6	954
7	944
8	1047
9	927
10	1144
11	1073
12	1016