QUESTION $4$

A forecasting method has produced the following over the past five months. What is the mean absolute deviation?

$\backslash$table$[[$Actual$,$Forecast$],[10,11],[8,10],[10,8],[6,6],[9,8]]$

$2\mathrm{.}0$

$1\mathrm{.}4$

$1\mathrm{.}0$

$1\mathrm{.}2$

$1\mathrm{.}6$