Answer
$6\sqrt {3}$ miles or $10.4$ miles.
Work Step by Step
The given function is
$d(x)=\sqrt {\frac{3x}{2}}$
The value of $x$ is $72$.
Plug into the function.
$d(72)=\sqrt {\frac{3(72)}{2}}$
Simplify.
$d(72)=\sqrt {3\cdot 36}$
$d(72)=\sqrt {3^2\cdot3\cdot2^2}$
$d(72)=3\cdot 2\sqrt {3}$
$d(72)=6\sqrt {3}$
Use a calculator to solve.
$d(72)=10.3923048454$
Round to the nearest tenth of a mile.
$d(72)=10.4$
