document.write( "Question 1072486: In a certain college, 33% of the physics majors belong to ethnic minorities. If 8 students are selected at random from the physics majors, what is the probability that more than 5 belong to an ethnic minority?
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\n" ); document.write( " 0.0659
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\n" ); document.write( " 0.9154
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\n" ); document.write( " 0.0187
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\n" ); document.write( " 0.0846
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Algebra.Com's Answer #687387 by Theo(13342)\"\" \"About 
You can put this solution on YOUR website!
this looks like a binomial probability type problem.\r
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\n" ); document.write( "\n" ); document.write( "the formula is:\r
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\n" ); document.write( "\n" ); document.write( "p(x) = p^x * q^(n-x) * c(n,x)\r
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\n" ); document.write( "\n" ); document.write( "p is the probability that a student is a minority.
\n" ); document.write( "this makes p = .33\r
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\n" ); document.write( "\n" ); document.write( "q is the probability that a student is not a minority.
\n" ); document.write( "this makes q = 1 - .33 = .67\r
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\n" ); document.write( "\n" ); document.write( "c(n,x) is the number of ways you can get x minority students out of n students.\r
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\n" ); document.write( "\n" ); document.write( "n is the total number of students.\r
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\n" ); document.write( "\n" ); document.write( "you have n = 8, p = .33 and q = .67\r
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\n" ); document.write( "\n" ); document.write( "c(n,x) is equal to n! / (x! * (n-x)!)\r
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\n" ); document.write( "\n" ); document.write( "you want to know the probability that more than 5 out of the 8 students will be a minority.\r
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\n" ); document.write( "\n" ); document.write( "this means you want to know the probability that 6 or 7 or 8 students out of 8 students is a minority.\r
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\n" ); document.write( "\n" ); document.write( "using the formula of p(x) = p^x * q^(n-x) * c(n,x), then you want the sum of:\r
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\n" ); document.write( "\n" ); document.write( "p(6) + p(7) + p(8)\r
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\n" ); document.write( "\n" ); document.write( "p(6) = .33^6 * .67^2 * c(8,6)
\n" ); document.write( "p(7) = .33^7 * .67^1 * c(8,7)
\n" ); document.write( "p(8) = .33^8 * .67^0 * c(8,8)\r
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\n" ); document.write( "\n" ); document.write( "c(8,6) = 8! / (6! * 2!) = 56/2 = 28
\n" ); document.write( "c(8,7) = 8! / (7! * 1!) = 8
\n" ); document.write( "c(8,8) = 8! / (8! * 0!) = 1\r
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\n" ); document.write( "\n" ); document.write( "formulas become:\r
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\n" ); document.write( "\n" ); document.write( "p(6) = .33^6 * .67^2 * 28 = .016233
\n" ); document.write( "p(7) = .33^7 * .67^1 * 8 = .00228
\n" ); document.write( "p(8) = .33^8 * .67^0 * 1 = .00014\r
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\n" ); document.write( "\n" ); document.write( "add these up and round to the 4th decimal place and you get:\r
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\n" ); document.write( "\n" ); document.write( "p(6) + p(7) + p(8) = .0187\r
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