$(15$ pts $)$ A large boiler for a $600$ megawatt $($MW$)$ power plant produce a sound power level of $149dB(re{10}^{-12}(W))$ at $4,000Hz,$ from the induced draft fans. Determine the sound pressure level $550\mathrm{.}0$ m downwind on a clear winter night when the wind speed is $4\mathrm{.}50\frac{m}{s},$ the temperature is $30\mathrm{.}0C,$ the relative humidity is $30$ percent, and the barometer pressure is $101\mathrm{.}3$ KPa $.$ The height of the boiler is $10$ m $.$ The height of the receiver is $2\mathrm{.}0$ m $.$ The ground surface characteristics are shown below: