The Following Seasonal Indexes and Trend Line Were Computed from Five

question 34

Essay

The following seasonal indexes and trend line were computed from five years of quarterly sales data.
Trend line: ŷt = 325 + 18.5t, t = 1, 2, 3, …20. $$\begin{array} { | c c | } \hline \text { Quarter } & \text { Seasonal index } \\\hline 1 & 1.35 \\2 & 1.22 \\3 & 0.88 \\4 & 0.55 \\\hline\end{array}$$ Forecast the sales for the next four quarters.