Consider the following data:

A$)$ Forecasting Method F$1$ produces more accurate forecasts or F$2.($Support your answer$)$

MAD $(F_1)=\frac{(90-87)+(91-91)+(85-82)}{3}=2$

MAD$(F_2)=\frac{(90-88)+(91-90)+(85-80)}{3}=2\mathrm{.}67$

FI has MAD is lower $=>$ more accurate forecasts

B$).$ Find $2-$S control limits for forecasting method F$1.$