Zeus Computer Chips, Incorporated used to have major contracts to produce low$-$density memory chips. The market has been declining during the past three years because of the new high$-$density chips, which it cannot produce, so Zeus has the unpleasant task of forecasting next year. Here is the demand over the past $12$ ?quarters:

QUARTER DEMAND QUARTER DEMAND QUARTER DEMAND

$1.)4,78553,48093,180$

$2.)3,48062,690102,085$

$3.)4,28573,480112,685$

$4.)2,98082,380121,685$

Use regression and seasonal indexes to forecast the demand for the next four quarters.