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Unformatted text preview: STAT 430/510 Lecture 2 STAT 430/510 Probability Hui Nie Lecture 2 May 27th, 2009 STAT 430/510 Lecture 2 Review The basic principle of counting provides us a powerful tool for counting the number of ways that things can happen. An ordered sequence of k distinct objects taken from a set of n objects is called a permutation of size k . The total number of permutations of size k from n objects is given by P k , n = n ! ( n k )! STAT 430/510 Lecture 2 Combinations An unordered subset of size k from a set of n distinct objects is called a combination . The number of combinations of size k from n distinct objects is denoted by n k . n k = P k , n k ! = n ! k !( n k )! STAT 430/510 Lecture 2 Example From a group of 5 women and 7 men, how many different committees consisting of 2 women and 3 men can be formed? Solution: 5 2 7 3 = 350 What if 2 of the men are feuding and refused to serve on the committee together?...
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This note was uploaded on 06/28/2009 for the course STAT 430 taught by Professor Krieger during the Summer '08 term at UPenn.
 Summer '08
 KRIEGER
 Counting, Probability

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