document.write( "Question 1125508: The names of four students are placed in a small box and two will be selected. Let 1, 2, 3 and 4 denote the students. What is the probability that:
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Algebra.Com's Answer #741847 by ikleyn(52781) $\"\"$ $\"About$

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\n" ); document.write( "The names of four students are placed in a small box and two will be selected. Let 1, 2, 3 and 4 denote the students. What is the probability that:\r
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document.write( "    In all, there are   =  = 6 groups of 2 students, that can be formed of 4 students.\r\n" );
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document.write( "    Of these 6 groups, exactly 3 groups contain \"3\".  They are  (3,1), (3,2), and (3,4).\r\n" );
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document.write( "    Thus the probability under the question a) is   = .\r\n" );
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\n" ); document.write( "\n" ); document.write( "b) 3 or 4 is selected ?\r
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document.write( "    There is ONLY ONE group of two students, which contain NEITHER \"3\"  NOR  \"4\".\r\n" );
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document.write( "    This group is (1,2).\r\n" );
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document.write( "    The rest 5 of 6 groups necessary / inevitably contain  EITHER \"3\"  OR  \"4\".\r\n" );
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document.write( "    Thus the probability under the question b) is  .\r\n" );
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\n" ); document.write( "\n" ); document.write( "c) 3 is not selected ? \r
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document.write( "    As we saw in the n. a), there are 3 groups of two students that contain \"3\".\r\n" );
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document.write( "    Hence, of the total possible 6 groups three contain \"3\", while 3 other do not.\r\n" );
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document.write( "    Thus the probability under the question c) is   = .\r\n" );
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