document.write( "Question 945890: Here is the final question for the assignment.\r
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\n" ); document.write( "A quality control inspector samples 4 computer chips from a box containing 12 computer chips. If the box contains 2 defective chips, in how many ways can he select a sample so that both defective chips are selected?\r
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Algebra.Com's Answer #577022 by Edwin McCravy(20056)\"\" \"About 
You can put this solution on YOUR website!
A quality control inspector samples 4 computer chips from a box containing 12 computer chips. If the box contains 2 defective chips, in how many ways can he select a sample so that both defective chips are selected?
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document.write( "There are 2 defective chips and 10 good chips.\r\n" );
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document.write( "1.  We choose the defective ones:\r\n" );
document.write( "That's \"2 choose 2\" = 2C2 = (2*1)/(2*1) = 1 way\r\n" );
document.write( "2.  We choose the 2 good chips:\r\n" );
document.write( "That's \"10 choose 2\" = 10C2 = (10*9)/(2*1) = 45 ways\r\n" );
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document.write( "That's 2C2*10C2 = 1*45 = 45 ways.\r\n" );
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document.write( "Checking:\r\n" );
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document.write( "Suppose the chips are A,B,C,D,E,F,G,H,I,J,X,Y\r\n" );
document.write( "where A through J are the 10 good chips and X and Y are the 2 defective ones.\r\n" );
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document.write( "Here are the 45 ways he can select 4 including the 2 defective chips\r\n" );
document.write( "X and Y: \r\n" );
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document.write( "1. {X,Y,A,B}\r\n" );
document.write( "2. {X,Y,A,C}\r\n" );
document.write( "3. {X,Y,A,D}\r\n" );
document.write( "4. {X,Y,A,E}\r\n" );
document.write( "5. {X,Y,A,F}\r\n" );
document.write( "6. {X,Y,A,G}\r\n" );
document.write( "7. {X,Y,A,H}\r\n" );
document.write( "8. {X,Y,A,I}\r\n" );
document.write( "9. {X,Y,A,J}\r\n" );
document.write( "10. {X,Y,B,C}\r\n" );
document.write( "11. {X,Y,B,D}\r\n" );
document.write( "12. {X,Y,B,E}\r\n" );
document.write( "13. {X,Y,B,F}\r\n" );
document.write( "14. {X,Y,B,G}\r\n" );
document.write( "15. {X,Y,B,H}\r\n" );
document.write( "16. {X,Y,B,I}\r\n" );
document.write( "17. {X,Y,B,J}\r\n" );
document.write( "18. {X,Y,C,D}\r\n" );
document.write( "19. {X,Y,C,E}\r\n" );
document.write( "20. {X,Y,C,F}\r\n" );
document.write( "21. {X,Y,C,G}\r\n" );
document.write( "22. {X,Y,C,H}\r\n" );
document.write( "23. {X,Y,C,I}\r\n" );
document.write( "24. {X,Y,C,J}\r\n" );
document.write( "25. {X,Y,D,E}\r\n" );
document.write( "26. {X,Y,D,F}\r\n" );
document.write( "27. {X,Y,D,G}\r\n" );
document.write( "28. {X,Y,D,H}\r\n" );
document.write( "29. {X,Y,D,I}\r\n" );
document.write( "30. {X,Y,D,J}\r\n" );
document.write( "31. {X,Y,E,F}\r\n" );
document.write( "32. {X,Y,E,G}\r\n" );
document.write( "33. {X,Y,E,H}\r\n" );
document.write( "34. {X,Y,E,I}\r\n" );
document.write( "35. {X,Y,E,J}\r\n" );
document.write( "36. {X,Y,F,G}\r\n" );
document.write( "37. {X,Y,F,H}\r\n" );
document.write( "38. {X,Y,F,I}\r\n" );
document.write( "39. {X,Y,F,J}\r\n" );
document.write( "40. {X,Y,G,H}\r\n" );
document.write( "41. {X,Y,G,I}\r\n" );
document.write( "42. {X,Y,G,J}\r\n" );
document.write( "43. {X,Y,H,I}\r\n" );
document.write( "44. {X,Y,H,J}\r\n" );
document.write( "45. {X,Y,I,J}\r\n" );
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document.write( "Edwin
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