document.write( "Question 916261: One cage contains 2 white mice and 3 black ones, and another cage contains 4 white mice and 3 black ones. A cage is chosen at random and three mice are selected. Find the expected number of white mice in the sample.\r
\n" ); document.write( "\n" ); document.write( "I keep getting the wrong answer for this problem, I thought you did the number of ways to choose three mice (0-3) and find their probabilities and then continue to find the mean and that was the answer?
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Algebra.Com's Answer #555992 by ewatrrr(24785)\"\" \"About 
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Cage1: 5mice, 2W, 3B , p(w) = 2/5)
\n" ); document.write( "Cage2: 7mice: 4W, 3B, p(w) = 4/7
\n" ); document.write( "cage1 0r cage2 is chosen at random and three mice are selected, n = 3
\n" ); document.write( "expected number of white mice
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\n" ); document.write( "0 P(x =0) = \"%283%2F5%29%282%2F4%29%281%2F3%29+%2B+%284%2F7%29+%283%2F6%29%282%2F5%29\" Choosing cage1 0r cage2
\n" ); document.write( "1 P(x=1) = +
\n" ); document.write( "2 P(x=2) = binompdf( 5, .4, 2) + binompdf(7, 4/7, 2) = similar to the above
\n" ); document.write( "3 P(x=3) = binompdf( 5, .4, 3) + binompdf(7, 4/7, 3) = \r
\n" ); document.write( "\n" ); document.write( "expected = 0•P(x =0) + 1•P(x =1) + 2•P(x =2) + 3•P(x =3)
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