document.write( "Question 875430: 37. A box is filled with 12 locks of which 4 are defective. All the locks look alike and have equal probability of
\n" ); document.write( "being defective. 3 locks are chosen and placed in a box. What is the probability that 2 locks are defective? \n" ); document.write( "
Algebra.Com's Answer #528162 by jim_thompson5910(35256)\"\" \"About 
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There are 12 C 3 = 220 ways to pick 3 locks from the pool of 12.\r
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\n" ); document.write( "\n" ); document.write( "There are 4 defective locks.\r
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\n" ); document.write( "\n" ); document.write( "There are 12-4 = 8 non-defective locks.\r
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\n" ); document.write( "\n" ); document.write( "There are (4 C 2)*(8 C 1) = (6)*(8) = 48 ways to pick 3 locks where 2 are defective and 1 is non-defective.\r
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\n" ); document.write( "\n" ); document.write( "Probability: (# of ways to pick 3 locks with 2 defective)/(# of ways total) = 48/220 = 12/55 \n" ); document.write( "
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