Pollution from a factory is entering a lake. The rate of concentration of the pollutant at time t is given by P′(t) = 140t^5/2, where t is the number of years since the factory started introducing pollutants into the lake. Ecologists estimate that the lake can accept a total level of pollution of 4850 units before all the fish life in the lake ends. Can the factory operate for 4 years without killing all the fish in the lake?