Considering the following data using moving average $(4$ quarters$),$ weighted moving average $(4$ quarters; $0\mathrm{.}4,0\mathrm{.}3,0\mathrm{.}2,$ and $0\mathrm{.}1$; where $0\mathrm{.}4$ is the weight for the most recent month$)$ and exponential smoothing $(\backslash$alpha $=0\mathrm{.}25,$ FApril$=100)$

a$)$ Calculate Mean Absolute Deviation $($MAD$)$ and SF for three forecasting techniques

b$)$ Which forecasting technique should be used to forecast the September demand?

c$)$ Find the $95\%$ confidence interval for the forecasted demand