In$$https:$//$docs$.$google.com$/$spreadsheets$/$d$/1-$Z$\_$YM$-0$VNdFIaLVca$17$L$6$r$8$x$8$xxy$56$ub$/$edit#gid$=844938275$Excel file$$you will find the sales data of a particular model of a snow blower for $20$ time seasons. Open the spreadsheet and complete the orange colored cells using the Winter's forecasting method with Alpha $0\mathrm{.}3$ and Gamma $0\mathrm{.}2.$ The rest of the cells were calculated for you.

What is the forecast for period $21?$ ANSWER: $[$ Select $]["44","47","49","42"]$

What is the Mean Absolute Error $($MAPE$)$ of the estimation: $[$ Select $]["14\mathrm{.}9\%","8\mathrm{.}9\%","12\mathrm{.}9\%","10\mathrm{.}9\%"]$