A manager has used an existing method to forecast the demand for gallons of ice cream for the past six periods. Demand and forecast amounts using this method are shown in the table below. The manager is now contemplating the use of the Simple Moving Average $($SMA$)$ method of size $2$ for demand forecasting. Would the SMA method of size $2$ produce better results that the existing method? For full credit show all steps and calculations in a spreadsheet. $(5$ points$)$

$\backslash$table$[[$Period$,$Demand,Forecast$],[1,90,87],[2,85,88],[3,91,87],[4,92,89],[5,95,90],[6,88,92]]$