Frances puts a hungry rat into an experimental chamber. whenever the rat presses a lever, food falls into a tray. in about 30 minutes, the rat is pressing the lever steadily. frances returns the rat to the training cage for one hour a day every day until the rat produces young. frances then trains one of this rat's offspring in the same manner as its mother and repeats this procedure for generation after generation. you predict that when the twelfth generation rat is put into the training cage, it will press the lever steadily in about