1. Consider a lake with volume 10.0106m3 that is fed by a stream with a flow rate of 5.0m3/s and pollution concentration of 10mg/L. There is also a sewage outfall that discharges 0.5m3/s of the same pollutant into the lake. The sewage has a concentration of 100mg/L. Assuming the pollution is completely mixed in the lake, and assuming no evaporation or other water losses or gains, find the steady-state concentration. (25 points)