Consider the sales data for Computer Success given in Problem $7.$

a$.$ Use a $3-$month weighted moving average to forecast the sales for the months April through December. Use weights of $(4/8),(3/8),$ and $(1/8),$ giving more weight to more recent data.

b$.$ Use exponential smoothing with $=0\mathrm{.}6$ to forecast the sales for the months April through December. Assume that the initial forecast for January was