Given reaction time t $=1\mathrm{.}0$s$,$ travel speed S $=40$ mi$/$hr on a $2\%$ downgrade intersection, if W $=40$ft$,$ L $=18$ft$,$ is $4$s yellow time long enough for a driverA, who is $250$ ft away from intersection, to pass stop line without accelerating? Can another driverB, who is $200$ ft away, make fully stop or safely clear the intersection?