Compute a forecast for period 11 to 15 using method of moving averages with 3 months of observations in each average. Compute the MAD for these forecasts.

Period	Netherland Index of production
1	100
2	99
3	96
4	95
5	94
6	98
7	98
8	96
9	97
10	98
11	96
12	95
13	96
14	97
15	99
16	99
17	95
18	94
19	89
20	100
21	90
22	87
23	89
24	93

Please Explain and show how to do this!