Answer
$\text{approximately }15.10\text{ }m$
Work Step by Step
Using the given formula $
h=\dfrac{0.00252d^{2.27}}{e}
,$ with $
d=50
,$ and $
e=1.2
,$ then
\begin{align*}
h&=\dfrac{0.00252(50)^{2.27}}{1.2}
\\\\&\approx
15.10
.\end{align*}
Hence, the optimal height, $h,$ of the letters of a message printed on pavement is $
\text{approximately }15.10\text{ }m
.$