1.Enceladus is the sixth-largest moon of Saturn. Enceladus is often called the protector of Saturn. Many meteorites that were supposed to fly to Saturn will be affected by the Enceladus's gravity and hit Enceladus. Now suppose that the probability of a meteorite being attracted by Enceladus and hitting Enceladus is 50%. When there are 1600 meteorites flying to Saturn, what is the probability that more than 400 meteorites and less than 1200 meteorites will hit Enceladus?