$$b$)$ Find the MAD based on the$2-$year moving average forecast in part$($a$).$

The value of MAD is computed by taking the sum of the absolute values of the individual forecast errors$($deviations$)$ and dividing by the number of periods of data$($n$)$:

MAD$=$ StartFraction Summation from nothing to nothing $|$Actual minus Forecast$|$ Over n EndFraction

$|$Actual $$ Forecast$|$

n

Part $6$

The absolute error for year $4$ is $100\mathrm{.}00100\mathrm{.}00$ miles$($round your response to two decimal$$ places$).$