QUESTION $13$

Twenty$-$eight $(28)$ pedestrians$/$cycle use a crosswalk to cross a $72-$ft wide street in both directions. The width of the crosswalk is $11$ ft$.$ How much $\backslash$tau $\_($i$,$ps$)$ should be set for these pedestrians? Use a walking speed of $3\mathrm{.}5$ ft$/$s$.$

$21\mathrm{.}2$ sec

$31\mathrm{.}0$ sec

$56\mathrm{.}0$ sec

$52\mathrm{.}8$ sec