three-year period:
2015
1
2
3
4
Demand
12
25
76
52
2016
1
2
3
4
Demand
16
32
71
62
2017
1
2
3
4
Demand
14
45
84
47
a. Determine the seasonal factors for each quarter by the seasonal decomposition method.
b. Based on the result of part (a), determine the deseasonalized demand series.
c. Predict the demand for the first quarter of 2018 for the deseasonalized series from a six-
quarter moving average.
Fig: 1