The following equation summarizes the trendportion of quarterly sales of condominiums over a long cycle. Sales also exhibit seasonal variations. Using the information given, prepare a forecast of sales for each quarter of next year (not this year), and the first quarters of the year following that.

F_t= 20 - 4t + t²

where

F_t= unit sales

t = 0 at the first quarter of last year.

Quarter Seasonal

variation

1 1.2

2 0.9

3 0.6

4 1.4