The Excel file Closing Stock Prices provides data for four stocks and the Dow Jones Industrial Average over a one$-$month period.

a$.$ Develop a spreadsheet model for forecasting Dow Jones Industrial Average prices using a simple two$-$period and three$-$period moving average. Compute MAD to determine which model is better?

b$.$ Develop a spreadsheet model for forecasting Dow Jones Industrial Average prices using simple exponential smoothing with a smoothing constant of $0\mathrm{.}1$ and $0\mathrm{.}5.$ Compute MAD to determine which model is better?