$=4\mathrm{.}47m$

$(3)$ A car initially moving at $10\mathrm{.}0$ mph took a distance $d$ to completely stop, with the brake pedal floored. On the same road in identical conditions, the next day, that car took a distance $d^{\text{'}}=2\mathrm{.}3d[2\mathrm{.}3$ times $d$ to attain a complete stop $($with floored brake pedal, again$).$ What was the car's initial velocity in the second case?