Answer
$\frac{\sqrt {210}}{2}\approx 7.25$ miles.
Work Step by Step
$d=\sqrt{\frac{3h}{2}}$ where $d$ is in miles and $h$ in feets.
Given that $h=35\text{ ft}$
$\implies d=\sqrt {\frac{3(35)}{2}}=\frac{\sqrt {105}}{\sqrt {2}}$ (we have used the quotient property of square roots).
$d=\frac{\sqrt {105}}{\sqrt {2}}\cdot \frac{\sqrt {2}}{\sqrt {2}}=\frac{\sqrt {210}}{2}$
$d=\frac{\sqrt {210}}{2}$ or about $7.25$ miles.
