The Wintergreen Company produces a product whose demand is highly seasonal. The most recent 16 quarters of demand data are shown below. Use the product’s actual demand for the most recent 16 quarters to produce a forecast for periods 17 through 20 using classical decomposition of a time series forecasting.
Period a t
1…………………………421
2…………………………183
3…………………………466
4…………………………113
5…………………………629
6…………………………277
7…………………………693
8…………………………170
9…………………………736
10…………………………323
11…………………………813
12…………………………197
13…………………………789
14…………………………350
15…………………………876
16…………………………214