1. Say we have 60 periods of monthly sales data. Make seasonal forecast model for the data:
   1. What should the forecast be for months 61 - 72?
   2. What is the MFE?
   3. What is the MAD?
   4. What is the MAPE
   5. What is the approximate standard deviation of forecast error?
   6. While forecasting, what is the first thing to be done?

Period	Demand	Period	Demand
1	968	31	1082
2	848	32	1298
3	866	33	1071
4	857	34	1213
5	823	35	1299
6	992	36	1324
7	1071	37	968
8	1310	38	901
9	1050	39	875
10	1190	40	815
11	1260	41	882
12	1365	42	992
13	988	43	1029
14	893	44	1260
15	910	45	1092
16	865	46	1109
17	823	47	1313
18	898	48	1338
19	1029	49	998
20	1260	50	928
21	1008	51	875
22	1178	52	874
23	1273	53	882
24	1420	54	983
25	978	55	1050
26	928	56	1323
27	857	57	1103
28	840	58	1132
29	815	59	1260
30	926	60	1351