Month	Sales
February	224
March	217
April	211
May	239
June	234
July	243
August	238
September	243
October	251
November	259
December	270

Month	Sales
January	260
February	284
March	280
April	271
May	302
June	286
July	297
August	301
September	309
October	314

a. Calculate the nave estimator, which is Sales t = Sales t 1 .b. Calculate the two-period and three-period moving averages.c. Calculate the mean absolute deviation for each of the forecasting methods.