document.write( "Question 388108: There are 6 boys and 4 girls and a group of 5 people must be formed. How many groups are possible consisting of 2 girls and 3 boys\r
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\n" ); document.write( "nCr=combination of n things taken r at a time= n!/((n-r)!*r!)
\n" ); document.write( "4C2 * 6C3
\n" ); document.write( "=6*20
\n" ); document.write( "=120 groups\r
\n" ); document.write( "\n" ); document.write( "If a group is chosen randomly from the 10 people, find the probability that the group will consist exactly of 2 girls and 3 boys.\r
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Algebra.Com's Answer #274440 by Theo(13342)\"\" \"About 
You can put this solution on YOUR website!
The probability that a group of 5 chosen out of a group of 10 will contain exactly 2 girls and 3 boys is equal to:
\n" ); document.write( "(C(6,3) * C(4,2)) / C(10,5)\r
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\n" ); document.write( "\n" ); document.write( "That becomes 120 / 252 = .476190476\r
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\n" ); document.write( "\n" ); document.write( "That is the number of ways you can get a group of 5 consisting of 2 girls and 3 boys divided by the total number of ways you can get a group of 5.\r
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\n" ); document.write( "\n" ); document.write( "It can also be calculated another way.\r
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\n" ); document.write( "\n" ); document.write( "The probability of getting bbbgg (3 boys picked first and then 2 girls) would be:\r
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\n" ); document.write( "\n" ); document.write( "6/10 * 5/9 * 4/8 * 4/7 * 3/6\r
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\n" ); document.write( "\n" ); document.write( "This becomes .0476190476\r
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\n" ); document.write( "\n" ); document.write( "You then need to multiply that by the number of different ways the group of 5 can be chosen.\r
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\n" ); document.write( "\n" ); document.write( "That would be C(5,2) = 10\r
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\n" ); document.write( "\n" ); document.write( "The total probability is therefore .0476190476 * 10 = .476190476\r
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\n" ); document.write( "\n" ); document.write( "The number of ways the group of 5 can be choen is shown below:\r
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\n" ); document.write( "\n" ); document.write( "bbbgg
\n" ); document.write( "bbgbg
\n" ); document.write( "bbggb
\n" ); document.write( "bgbbg
\n" ); document.write( "bgbgb
\n" ); document.write( "bggbb
\n" ); document.write( "gbbbg
\n" ); document.write( "gbbgb
\n" ); document.write( "gbgbb
\n" ); document.write( "ggbbb\r
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\n" ); document.write( "\n" ); document.write( "bbbgg means boy drawn first and second and third girl drawn fourth and fifth.
\n" ); document.write( "bbgbg means boy drawn first and second girl drawn third boy drawn fourth girl drawn fifth.
\n" ); document.write( "etc. until you get to:
\n" ); document.write( "ggbbb means girls drawn first and second boy drawn third fourth and fifth.\r
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\n" ); document.write( "\n" ); document.write( "both ways will get you the same answer.\r
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