2. A popular brand of tennis shoe has had the following demand history by quarters over a

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.