$3.$ Demand for an item for a nine$-$month period $($Jan$-$Sept$)$ is tabulated below. Your manager wants to test

two forecasting method is better over the period.

a$.$ Forecast Apr$-$Sept using three$-$month moving average

b$.$ Use exponential smoothing method with an alpha of $0\mathrm{.}3$ to estimate Apr$-$Sept using the average of

Jan through Mar as the initial forecast of Apr.

c$.$ Use MAD to decide which method produced the better forecast over the six month period.

Month Demand

January $110$

February $130$

March $150$

April $170$

May $160$

June $180$

July $140$

August $130$

September $140$