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 $\overline{MQ}$ is 2.5 and the length of $\overline{QP}$ is 6.4, what is the length of $\overline{NQ}$?