PROBLEM $1$: $(20$ marks$).$ 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 each of the stock prices using simple exponential smoothing with a smoothing constant of $0\mathrm{.}3.(5$ marks$)$

b$.$ Compare your results to the output from Excel's Data Analysis tool. $(5$ marks$)$

c$.$ Compute MAD, MSE, and MAPE. $(5$ marks$)$

d$.$ Does a smoothing constant of $0\mathrm{.}1$ or $0\mathrm{.}5$ yield better results? $(5$ marks.