H is forecasting its sales for next year using a combination of time series and regression analysis models. An analysis of past sales units has produced the following equation for the quarterly sales trend: y : 26x + 8,850 where the value of x represents the quarterly accounting period and the value of y represents the quarterly sales trend in units. Quarter 1 of next year will have a value for x of 25, quarter 2 - 26 and so on. The quarterly seasonal variations have been measured using the multiplicative (proportional) model and are