document.write( "Question 1195011: In an urn there are 3 white and 4 black marbles. They are taken out of the urn one by one. What is the chance of the first and last marble being white? \n" ); document.write( "

Algebra.Com's Answer #827351 by ikleyn(52781) $\"\"$ $\"About$

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\n" ); document.write( "In an urn there are 3 white and 4 black marbles. They are taken out of the urn one by one.
\n" ); document.write( "What is the chance of the first and last marble being white?
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document.write( "In all, there are 3+4 = 7 marbles.\r\n" );
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document.write( "There are   = 35 possible DISTINGUISHABLE permutations of these marbles. \r\n" );
document.write( "It is the number of all possible distinguishable outcomes of the experiment.\r\n" );
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document.write( "Of these 35 distinguishable permutations, there are 5 distinguishable permutations, \r\n" );
document.write( "where white marbles are in the 1-st and in the last, 7-th position, and in some \r\n" );
document.write( "position between 2-nd and 6-th for the remaining third white marble.\r\n" );
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document.write( "Therefore, the sough probability is  P =  = .    ANSWER\r\n" );
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