The sound level measured at various locations in an urban area is given in the table.
The average sound level for that area is $\_\_\_\_$ dBA (rounded off to two decimal places).
$$\begin{array}{|l|l|l|l|l|}
\hline
\textbf{Location} & A & B & C & D \\
\hline
\begin{array}{l}
\text{Sound level} \\
(\text{dBA})
\end{array}
& 40 & 55 & 65 & 75 \\
\hline
\end{array}$$
