City water, which is slightly chlorinated, is being used to flush a tank of heavily chlorinated water. The concentration C = C(t) of the chlorine in the tank t hours after flushing begins is given by the following formula. C=0.3 +2.77e-0.33t milligrams per gallon (a) What is the initial concentration of chlorine in the tank? C( mg/gal (b) Express the concentration of chlorine in the tank after 4 hours using functional notation. ) Calculate the concentration of chlorine in the tank after 4 hours. (Round your answer to two decimal places.) mg/gal