Answer
$4,000,000\ \ \mathrm{ft} $
Work Step by Step
By Exercise $70$, the highest point is $\displaystyle \frac{v_{0}^{2}}{64}$ feet above the starting point.
$\displaystyle \frac{v_{0}^{2}}{64}=\frac{(16,000)^{2}}{64}=4,000,000\ \ \mathrm{ft}$
