A swimming pool whose volume is 10 comma 000 gal contains water that is 0.02​% chlorine. Starting at t=​0, city water containing 0.001​% chlorine is pumped into the pool at a rate of 5 ​gal/min. The pool water flows out at the same rate. What is the percentage of chlorine in the pool after 1 hour​? When will the pool water be 0.002​% ​chlorine?