T102 SECTION 9.5 Permut &amp; Combin

# N r

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Unformatted text preview: at if we only need to choose PART of the group and arrange that part in as many ways possible? For instance, suppose that we need to choose a president, vice‐president, secretary, and treasurer from a group of 10 people (no person can hold more than 1 office). How many ways can this be done? (See previous page where we used the Fundamental Counting Principle): FORMULA FOR PERMUTING “n CHOOSE r” OBJECTS OR nPr (NO LIKE OBJECTS) If n objects are chosen r at a time, then the number of possible permutations, denoted nPr is: nPr = n! (n r )! What you have just found is 10 P4 – the number of permutations possible from “10 items choose 4 at a time”. Now, let’s choose a president, vice‐president, secretary, and treasurer from a group of 10 people using the above formula. EXAMPLES: 1. How many ways could you arrange 4 out of 9 ballerinas in a line? 2. A baseball team has 9 players. Find the number of ways the manager can arrange the batting order. 3. How many ways could you arrange the letters in the word RED? B. PERMUTATIONS INVOLVING LIKE OBJECTS Whenever t...
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## This document was uploaded on 03/12/2014 for the course T 102 at Indiana SE.

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