document.write( "Question 388629: 3) A class has 28 students. There are 5 good students, 13 fairly good students and 10 medium students. Randomly take 4 students to attend the meeting. Find the probability to have at least 2 good students that was chosen.\r
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Algebra.Com's Answer #275011 by Edwin McCravy(20056) $\"\"$ $\"About$

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3) A class has 28 students. There are 5 good students, 13 fairly good students and 10 medium students. Randomly take 4 students to attend the meeting. Find the probability to have at least 2 good students that was chosen.
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document.write( "The denominator of the desired probability is 28 choose 4 or 28C4.\r\n" );
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document.write( "It is easier to get the probability of the complement event and then \r\n" );
document.write( "subtract from 1.\r\n" );
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document.write( "The complement event is that either \r\n" );
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document.write( "A. all 4 students were chosen from the 13+10 or 23 non-good students\r\n" );
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document.write( "or\r\n" );
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document.write( "B. 1 good student was chosen from the 5 and the other 3 were chosen from\r\n" );
document.write( "   the 23 non-good students.\r\n" );
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document.write( "P(A or B) = P(A)+P(B) =  + \r\n" );
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document.write( "=   +  = 0.4324997548\r\n" );
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document.write( "That's the probability of the complement event.\r\n" );
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document.write( "The desired probability is therefore 1 - 0.4324997548 = 0.5675002452\r\n" );
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document.write( "Edwin

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