In the figure above, $△MNP$ is a right triangle with $\angle MNP=90^{\circ }$. $\overline{NQ}$ is an altitude to the hypotenuse $\overline{MP}$. If the length of $\overline{MN}$ is 3 and the length of $\overline{NP}$ is 4, what is the length of $\overline{MQ}$?