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Unformatted text preview: Solution of Homework 9 : Discrete Probability Q1. Show that if A and B are independent events, then A and B are also independent events. Answer P ( ¯ A ) P ( ¯ B ) = parenleftBig 1 P ( A ) parenrightBigparenleftBig 1 P ( B ) parenrightBig = 1 P ( A ) P ( B ) + P ( A ) P ( B ) = 1 parenleftBig P ( A ) + P ( B ) P ( A ) P ( B ) parenrightBig = 1 parenleftBig P ( A ) + P ( B ) P ( A ∩ B ) parenrightBig A,B are independent = 1 P ( A ∪ B ) = P ( A ∪ B ) = P ( A ∩ B ) → A, B are independent Note that this was only one way to prove it and there are several other alternatives. Q2. What is the probability of a fivecard poker hand contains the ace of hearts? Answer Let E be the event that a fivecard poker hand contains the ace of hearts. The number of elements in the event E is the number of ways to pick the other four cards, which is C (51 , 4). ∴ P ( E ) =  E   S  = C (51 , 4) C (52 , 5) = 5 52 ....
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This homework help was uploaded on 04/19/2008 for the course CS 182 taught by Professor W.szpankowski during the Fall '08 term at Purdue.
 Fall '08
 W.Szpankowski

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