$1.$ Why is forecasting necessary in Operations and Supply Chain Management $($OSCM$),$ and how does the common saying, "The only thing certain about a forecast is that it will be wrong," reflect the challenges of forecasting accuracy?

$2.$

Here are the actual tabulated demands for water bottles for a nine$-$month period $($January through September$).$ Your supervisor wants to test two forecasting methods to see which method was better over this period.

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a$.$ Forecast April through September using a three$-$month moving average.

b$.$ Using a weighted moving average, what is the forecast for September with weights of $\mathrm{.}20,\mathrm{.}30,$ and $\mathrm{.}50$ for June, July, and August, respectively?

c$.$ Use simple exponential smoothing with an alpha of $\mathrm{.}3$ to estimate April through September, using the average of January through March as the initial forecast for April.

d$.$ Using linear regression, forecast sales for September.

e$.$ Use MAD to decide if the three$-$month moving average or simple exponential smoothing produced the better forecast over the six$-$month period. $($Only compare these two model types$)$