Answer
$347.89$
Work Step by Step
Given \begin{equation}
c=340.3 \sqrt{\frac{T+273.15}{288.15}}.
\end{equation} Set $T = 28$ to find the speed of sound at sea level.
\begin{equation}
\begin{aligned}
c&=340.3 \sqrt{\frac{28+273.15}{288.15}}\\
&=340.3 \cdot \left(1.0223089\right)\\
& = 347.89.
\end{aligned}
\end{equation} The speed of sound at sea level is about $347.89$.
