Answer
The average velocity is $25.5~km/h$
Work Step by Step
We can find the east component of the displacement:
$3.2~km+(4.8~km)~sin~15.0^{\circ}+3.2~km = 7.64~km$
We can find the north component of the displacement:
$(4.8~km)~cos~15.0^{\circ} = 4.64~km$
We can find the magnitude of the displacement:
$\sqrt{(7.64~km)^2+(4.64~km)^2} = 8.94~km$
We can find the average velocity $v_{av}$:
$v_{av} = \frac{displacement}{time}$
$v_{av} = \frac{8.94~km}{0.35~h}$
$v_{av} = 25.5~km/h$
The average velocity is $25.5~km/h$
