##### 问题：In a set of 20 books，two books are defective, and the remaining eighteen are good, a publisher randomlyselects four of the 20 books with replacement and classifies each as defectives or good. determine the number of possible outcomes for this experiment?

In a set of 20 books，two books are defective, and the remaining eighteen are good, a publisher randomlyselects four of the 20 books with replacement and classifies each as defectives or good. determine the number of possible outcomes for this experiment?