document.write( "Question 851271: There are 9 students in a class: 7 boys and 2 girls.\r
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Algebra.Com's Answer #771012 by ikleyn(52786) $\"\"$ $\"About$

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document.write( "In this problem, the space of events is the set of all possible different groups of 3 persons that can be formed of 7+2 = 9 students.\r\n" );
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document.write( "The number of such groups is   =  = 84.\r\n" );
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document.write( "It is the number of events in the space of events.\r\n" );
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document.write( "Of them, the favorable set is the set of all different groups that can be formed of 7 boys.\r\n" );
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document.write( "The number of such groups is   =  = 35.\r\n" );
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document.write( "The probability under the problem's question is the ratio of the numer of favorable events (35) to the number of all possible outcomes (84)\r\n" );
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document.write( "    P =  =  = 0.4167 = 41.67%  (approximately).    ANSWER\r\n" );
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document.write( "The probability that the first selected student is a boy is  .\r\n" );
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document.write( "If the first selected student is a boy, then the probability that the second selected student is a boy is  .\r\n" );
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document.write( "If the first and the second selected students are boys, then the probability that the third selected student is a boy is  .\r\n" );
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document.write( "Thus the probability under the problem's question is\r\n" );
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document.write( "     = 0.4167 = 41.67%.\r\n" );
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