At 4:00 PM $\mathrm{mi} / \mathrm{h}^{2}$ at 4:15 It Reads 72

Short Answer

At 4:00 P.M. a car's speedometer reads 25 $\mathrm{mi} / \mathrm{h}^{2}$ . At 4:15 it reads 72 $\mathrm{mi} / \mathrm{h}^{2}$ . At some time between 4:00 and 4:15 the acceleration is exactly x $\mathrm{mi} / \mathrm{h}^{2}$ . Find x.