(a) A 9,760-gallon reservoir near the coast was built before the desalination water treatment plant and distribution piping to the city were complete. The plant was capable of producing water with zero salt concentration, but would blend the water later with sea water to yield 150mg/L. However, this is not your concern of this problem. To ensure that the new concrete walls of the reservoir would not be exposed to direct sunlight for extended periods, it was filled with sea water (salt concentration 30,205mg/L ). Once the treatment plant started operating, the plant manager had to reduce the salt concentration to 1,746mg/L before the water could be delivered to the customers. Note: 1 gallon =3.785 liters (clearly, these two numbers have the same precision) The manager planned to start flushing it out by keeping the tank well mixed while running in a hose with desalinated water at a flowrate of 71.5 gallons per minute and keeping the volume in the tank constant. What will be the time (in minutes) to reach the desired concentration of 1,746mg/L ? (Write your answers up to 3 significant digits) (b) The plant manager (as mentioned in Question 2) planned another way by emptying out some of the contaminated water and fill the tank up again with enough clean water to get 1,390mg/L. the maximum rate at which the tank will empty is 110 gallons per minute, and the maximum flow of clean water is 79.1 gallons per minute. What will be the total time (in minutes) in this case to reach the desired concentration 1,390 mg/L ? (Write your answer up to 3 significant digits.) The initial concentration in the tank is 35,479mg/L and the tank volume is 6,295 gallons