A simple forecasting method for weekly sales of flash drives used by a local computer dealer is to

form the average of the two most recent sales figures. Suppose sales for the drives for the past $12$

weeks were

a$.$ Determine the one$-$step$-$ahead forecasts made for periods $3$ through $12$ using this method.

b$.$ Determine the forecast errors for these periods.

c$.$ Compute the MAD, and the MSE based on the forecast errors computed in part $($b$).$

$=0\mathrm{.}15.$ To get the method started, use the forecast for week $4$ that you calculated in part a$.$

c$.$ Based on MAD, which method performed better?