A bird watcher meanders through the woods, walking $1\mathrm{.}55$ km due east, $0\mathrm{.}275$ km due south, and $3\mathrm{.}97$ km in a direction $\backslash (75\mathrm{.}9^\{\backslash$circ$\}\backslash )$ north of west. The time required for this trip is $1\mathrm{.}562$ h $.$ Determine the magnitudes of the bird watcher's $($a$)$ displacement and $($b$)$ average velocity.

$($a$)$ Number

Units

$($b$)$ Number

Units