Answer
$(-1.5\hat{i}+0.50\hat{k})\,m/s^{2}$
Work Step by Step
Average acceleration vector=$\frac{change\,in\,velocity\,vector}{time\,interval}$
$=\frac{((-2.0-4.0)\hat{i}+(-2.0-(-2.0))\hat{j}+(5.0-3.0)\hat{k})\,m/s}{4.0\,s}$
$=(-1.5\hat{i}+0.50\hat{k})\,m/s^{2}$
