Answer
Please see the work below.
Work Step by Step
We know that the average velocity is given as
(a) $v=\frac{r_2-r_1}{\Delta t}$
We plug in the known values to obtain:
$v=\frac{(4.6i+1.9k)-(2.2i+3.7j-1.2K)}{6.2}$
$v=\frac{2.4i-3.7j+3.1k}{6.2}$
$v=0.39i+0.60j+0.50k \space \frac{\mu m}{s}$
(b) The average speed is
$v=\sqrt{(0.39)^2+(0.60)^2+(0.50)^2}$
$v=0.87\frac{\mu m}{s}$
