$($b$)$ Which one of the four possible forecasts mentioned in part $($a$)(3-$week and $6-$week simple moving average and exponential smoothing with value of $\backslash$alpha $=0\mathrm{.}2$ and $\backslash$alpha $=0\mathrm{.}6)$ is the best forecast? Justify your answer by calculating $($Mean Absolute Deviation$)$ MAD and $($Mean Squared Error$)$ MSE. According to the chosen forecasting method, what will be the forecast of sales during Week $31?$