3 2) (Calculation: 30 points) (Calculations) A lake with a constant volume of 5.0x10 mis fed by a polluted stream with a flow rate of 4.32 x 10 m/ day and a pollutant concentration of 10.0 mg/L. A 1.0-meter diameter sewer line, flowing half full, is also discharging into the lake at a constant rate of 0.43 x 105 m3/day with a pollutant concentration of 80.0 mg/L. The wastes from both sources have a first order degradation rate of 0.010/hr. Assume that the lake is well mixed and that there are no other significant losses or sources of water or waste. a. (20 points) What will be the pollutant concentration in the lake? b. (5 points) What will be the pollutant concentration flowing out of the lake? c. (5 points) What is the velocity of flow in the pipe in m/s? a