The following trend line and seasonal indexes were computed from 10 years of quarterly observations. Forecast the

Question:

The following trend line and seasonal indexes were computed from 10 years of quarterly observations. Forecast the next year’s time series.

ŷ = 150 + 3t t = 1, 2, . . . , 40

Quarter................................................ Seasonal Index
1................................................................ .7
2................................................................ 1.2
3................................................................ 1.5
4................................................................ .6