Given the following data:

Prepare a forecast using smoothing constant $=0\mathrm{.}40.$

a$)$ Subjective estimate $($for this example, use $60).$

b$)$ First actual value $($na$$ve approach$).$Given the following data, compute MAD, MSE, and MAPE for the following data. Then, please compute the standard deviation of forecast error using the first eight months.

$\backslash$table$[[$Months$,$Demand,Forecast$],[1,210,222],[2,240,235],[3,230,225],[4,240,245],[5,280,265],[6,222,250],[7,220,220],[8,250,273]]$