A manufacturing plant located in a narrow canyon has applied to the Environmental Protection Agency for a permit to continuosly release 15 ft^3/min of exhaust gas, containing 0.06 gmol/ft^3 of a pollutant, into the air. The wind travels through the canyon at an average flow rate of 800 ft^3/min (not including the exhaust gas). Furthermore, some of the pollutant settles out on the ground and foliage (the change in volume of air because of this settling is negligible) so that 20% of the pollutant released setles out by the time the air leaves the canyon.

a) What will be the average concentration of the pollutant in the air coming out of the canyon,?

b) what wind flow rate entering the canyon would produce a pollutant concentration greater than 0.0025 gmol/ft^3 in the air coming out of the canyon?