Answer
$\beta=99$ dB
Work Step by Step
To find sound level, the formula using intensity and sound level must be used. This formula is $$\beta=10log(\frac{I}{I_o})$$ where $I_o$ is the threshold of hearing, $1.0 \times 10^{-12}W/m^2$. Substituting value of $I_o$ and $I=0.0080W/m^2$ yield $$\beta=10log(\frac{0.0080W/m^2}{1.0
\times 10^{-12}W/m^2})=99dB$$
