document.write( "Question 936012: Seven cards numbered 1 to 7 are shuffled thoroughly. The top two cards are turned face up on a table. Draw a probability tree diagram and use it to calculate the probability that the numbers will \r
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Algebra.Com's Answer #569423 by Edwin McCravy(20056)\"\" \"About 
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document.write( "We can't do tree diagrams on here.  \r\n" );
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document.write( "There are C(7,2) = (7*6)/(2*1) = 21 ways the two top cards can occur.\r\n" );
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document.write( "There are only 3 even numbered cards [2,4,6}, so there are only\r\n" );
document.write( "C(3,2) = (3*2)/(2*1) = 3 ways both top cards can be even.  They\r\n" );
document.write( "are {2,4}, {2,6}, and (4,6}. \r\n" );
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document.write( "So the probability that both will be even is 3/21 or 1/7.\r\n" );
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document.write( "To have an odd sum, one card must be even and the other odd.\r\n" );
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document.write( "We can pick the odd card 4 ways {1,3,5,7}\r\n" );
document.write( "We can pick the even card 3 ways (2,4,6}\r\n" );
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document.write( "That's 4*3 = 12 ways to pick them so that the sum will be odd.\r\n" );
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document.write( "So the probability that the sum will be odd is 12/21 = 4/7.\r\n" );
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document.write( "You'll have to ask your teacher how he wants you to draw\r\n" );
document.write( "a tree diagram to figure this out, but the answers are 1/7\r\n" );
document.write( "and 4/7.\r\n" );
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document.write( "Edwin
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