The data in the table below represent warehouse club and superstore sales in the eastern and central United States on a monthly basis. The data are in millions of dollars.

a. Prepare a time-series plot of the data, and visually inspect that plot to determine the trend characteristics in this series.

b. Use and exponential smoothing model to develop a forecast of sales for the next 12 months, and explain which forecasting model is the best choice. Plot the actual and forecast values. Determine the MAPE for the model during the historical period.

Date	Sales
Jan-02	2,580
Feb-02	2,616
Mar-02	2,838
Apr-02	2,985
May-02	3,258
Jun-02	3,107
Jul-02	3,097
Aug-02	3,288
Sep-02	3,077
Oct-02	3,429
Nov-02	4,011
Dec-02	5,739
Jan-03	2,877
Feb-03	2,885
Mar-03	3,259
Apr-03	3,454
May-03	3,771
Jun-03	3,667
Jul-03	3,743
Aug-03	3,792
Sep-03	3,699
Oct-03	4,082
Nov-03	4,727
Dec-03	6,672
Jan-04	3,560
Feb-04	3,575
Mar-04	4,220
Apr-04	4,282
May-04	4,594
Jun-04	4,691
Jul-04	4,629
Aug-04	4,795
Sep-04	4,632
Oct-04	5,067
Nov-04	5,746
Dec-04	7,965
Jan-05	4,317
Feb-05	4,118
Mar-05	4,855
Apr-05	4,999
May-05	5,343
Jun-05	5,392
Jul-05	5,274
Aug-05	5,435
Sep-05	5,217
Oct-05	5,460
Nov-05	6,288
Dec-05	8,403
Jan-06	4,758
Feb-06	4,914
Mar-06	5,431
Apr-06	5,474
May-06	6,124
Jun-06	6,027
Jul-06	5,914
Aug-06	6,244
Sep-06	5,808
Oct-06	6,373
Nov-06	6,994
Dec-06	9,018
Jan-07	5,694
Feb-07	5,431
Mar-07	6,240
Apr-07	6,101
May-07	6,849
Jun-07	6,694
Jul-07	6,815
Aug-07	6,948
Sep-07	6,450
Oct-07	7,190
Nov-07	7,738
Dec-07	9,769
Jan-08	6,665
Feb-08	6,400
Mar-08	7,277
Apr-08	7,584
May-08	8,169
Jun-08	8,179
Jul-08	8,118
Aug-08	8,284
Sep-08	7,962
Oct-08	8,636
Nov-08	9,433
Dec-08	11,786
Jan-09	8,082
Feb-09	7,761
Mar-09	8,994
Apr-09	8,803
May-09	9,712
Jun-09	9,843
Jul-09	9,769
Aug-09	9,944
Sep-09	9,582
Oct-09	10,209
Nov-09	11,115
Dec-09	14,995
Jan-10	9,183
Feb-10	9,478
Mar-10	10,751
Apr-10	10,518
May-10	11,349
Jun-10	11,728
Jul-10	11,590
Aug-10	11,871
Sep-10	11,336
Oct-10	11,986
Nov-10	13,130
Dec-10	16,694
Jan-11	11,195
Feb-11	10,919
Mar-11	12,389
Apr-11	12,619
May-11	13,489
Jun-11	13,620
Jul-11	13,438
Aug-11	14,084
Sep-11	13,172
Oct-11	14,040
Nov-11	15,759
Dec-11	19,992
Jan-12	13,162
Feb-12	13,394
Mar-12	15,285
Apr-12	14,467
May-12	16,086
Jun-12	16,027
Jul-12	15,622
Aug-12	16,360
Sep-12	14,714
Oct-12	15,894
Nov-12	18,152
Dec-12	22,089
Jan-13	15,161
Feb-13	15,342
Mar-13	16,997
Apr-13	16,623
May-13	18,064
Jun-13	17,605
Jul-13	17,746
Aug-13	18,907
Sep-13	16,735
Oct-13	18,146
Nov-13	20,336
Dec-13	24,665
Jan-14	17,686
Feb-14	17,908
Mar-14	18,691
Apr-14	19,030
May-14	20,623
Jun-14	19,596
Jul-14	20,122
Aug-14	20,029
Sep-14	18,669
Oct-14	20,518
Nov-14	21,967
Dec-14	27,584
Jan-15	19,315
Feb-15	19,186
Mar-15	21,211
Apr-15	20,985
May-15	22,385
Jun-15	22,223
Jul-15	22,602
Aug-15	22,456
Sep-15	21,418
Oct-15	23,092
Nov-15	24,598
Dec-15	30,706
Jan-16	21,692
Feb-16	21,699
Mar-16	23,402
Apr-16	24,046
May-16	24,881
Jun-16	24,602
Jul-16	24,631
Aug-16	24,831
Sep-16	23,603
Oct-16	24,608
Nov-16	26,705
Dec-16	34,023
Jan-17	23,837
Feb-17	23,438
Mar-17	26,305
Apr-17	25,429
May-17	27,152
Jun-17	27,218
Jul-17	26,722