The Entrepreneurship professor had a habit of oversupplying extra credit opportu$-$

nities for his class each semester and his colleagues delighted in trying to forecast

his class enrollment from one semester to the next. The forecasts for one colleague,

along with the actual class enrollment, appear in the table.

$($a$)$ Calculate the MAD for this scenario. $(4$ points$)$

$($b$)$ Calculate the MSE for this scenario. $(4$ points$)$

$($c$)$ What is the largest value for the tracking signal $($either under or overforecast$-$

ing$)?(4$ points$)$

$($d$)$ What is the mean absolute percentage error? $(4$ points$)$