document.write( "Question 269858: An urn contains 10 balls: 4 red and 6 blue. A second urn contains 16 red balls and an unknown number of blue balls. A single ball is drawn from each urn. The probability that both balls are the same colour is 0.44. Calculate the number of blue balls in the second urn. \n" ); document.write( "

Algebra.Com's Answer #197725 by Edwin McCravy(20060) $\"\"$ $\"About$

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An urn contains 10 balls: 4 red and 6 blue. A second urn contains 16 red balls and an unknown number of blue balls. A single ball is drawn from each urn. The probability that both balls are the same colour is 0.44. Calculate the number of blue balls in the second urn.
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document.write( "Suppose there are N blue balls.\r\n" );
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document.write( "Then \r\n" );
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document.write( "P(Red from first urn) = \r\n" );
document.write( "P(Red from second urn) = \r\n" );
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document.write( "P(Red from 1st Urn AND Red from 2nd Urn) = \r\n" );
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document.write( "P(Blue from first urn) = \r\n" );
document.write( "P(Blue from second urn) = \r\n" );
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document.write( "P(Red from 1st Urn AND Red from 2nd Urn) = \r\n" );
document.write( "P(Blue from 1st Urn AND Blue from 2nd Urn) = \r\n" );
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document.write( "P(Same color) = \r\n" );
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document.write( "P[(Red from 1st Urn AND Red from 2nd Urn) OR (Blue from 1st Urn AND Blue from 2nd Urn)] = \r\n" );
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document.write( "P(Red from 1st Urn AND Red from 2nd Urn) + P(Blue from 1st Urn AND Blue from 2nd Urn)] =\r\n" );
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document.write( "We are told this equals \r\n" );
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document.write( "Can you solve that equation for N?  If not post again asking\r\n" );
document.write( "how to solve it.\r\n" );
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document.write( "Answer N=4.  So there are 4 blue balls.\r\n" );
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document.write( "Edwin

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