Use the Excel file accompanied in this assignment to answer this question. The historical data includes a product$$s

sales for the past years.

$($a$)$ Plot the sales data with respect to time $($select the two columns; then from Insert ribbon, click on Recommended

Charts and select Scatter plot; it should show demand points over time connected to one another with straight lines$).$

Before computing the MAD for each forecasting method, and by observing the plot only, try to guess whether a $5-$

period or a $9-$period moving average method is a better forecast $($it is ok if your guess is not aligned with your

answer in part $($b$)$ as long as you provide correct reasonings for your conclusions$).$ Hint: study Week $12-$Friday$$s

lecture notes if you missed that lecture or don$$t remember the discussion around advantages of larger$/$smaller n

values.

$($b$)$ Which forecast method among the following four do you recommend: $5-$period and $9-$period moving averages,

and exponential smoothing with $=0\mathrm{.}2$ and $=0\mathrm{.}9?$ Justify your answer by calculating MADs in Excel. Briefly

explain $($read the blue paragraph above for a clearer description of what you need to submit for this question$).$