The following equation summarizes the trend portion 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 quarter of the year following that.
Ft = 40 6.5t + 2t2
where
Ft = Unit sales
t = 0 at the first quarter of last year
Quarter Relative
1 ........... 1.1
2 ........... 1.0
3 ........... .6
4 ........... 1.3