Answer
The magnitude of $v$ is 87 mi/s
Work Step by Step
$v_r = 67~mi/s$
$v_t = 55.64~mi/s$
We can find the magnitude of $v$:
$v = \sqrt{v_r^2+v_t^2}$
$v = \sqrt{(67~mi/s)^2+(55.64~mi/s)^2}$
$v = 87~mi/s$
The magnitude of $v$ is 87 mi/s