# People with good hearing can perceive sounds as low in level as –8.00 dB at a frequency of 3000 Hz. What is the intensity of this sound in watts per meter squared?

$I \left(\mathrm{dB}\right) = 10 \log \left(\frac{I}{I} _ 0\right)$
Where ${I}_{0} = {10}^{- 12} \frac{W}{m} ^ 2$ represents the intensity just audible (correspnding to $0 \mathrm{dB}$).
$- 0.08 = 10 \log \left(\frac{I}{10} ^ \left(- 12\right)\right)$; power $10$ both sides and rearrange:
$I = 9.8 \times {10}^{-} 13 \frac{W}{m} ^ 2$