The last four weekly values of sales were $80,100,105,$ and $90$ units, respectively. The last four forecasts $($for the same four weeks$)$ were $60,80,95,$ and $75$ units, respectively. Calculate the MAPE for these four weeks.

$\backslash$table$[[$Sales$,$Forecast,Error,Error squared Pct$.$ error,$],[80,60,20,400,\mathrm{.}25],[100,80,20,400,\mathrm{.}20],[105,95,10,100,\mathrm{.}095],[90,75,15,225,\mathrm{.}167]]$

$281\mathrm{.}25$

$1\mathrm{.}78$

$16\mathrm{.}25$

$77\mathrm{.}5$

$93\mathrm{.}75$

$17\mathrm{.}8$