STAT 263 Lecture 10: Chapter 5
22 May 2017
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If a choice consists of k steps, of which the first choice can be made n1 ways, second step n2 ways, and so on; the whole choice can be made (cid:2869) (cid:2870) (cid:3038) ways. We can visualize this using a tree diagram: 52 51 50 1=52! How many ways can select a class president, vice president, and secretary from a class of 80 students 80p3 = 492,960. Permutations: r objects selected from a set of n distinct objects npr (shift + on calculator) Combinations: r objects selected from a set of n distinct objects ncr (shift + on calculator) and can be written (cid:3435)(cid:3041)(cid:3045)(cid:3439) To get the permutation from the combination we can multiply by ! How many ways can a committee of 3 students be chosen from a class of 80 (all students chosen will be on the committee, it doesn"t matter in which order they were chosen)
