document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1039944>Question 1039944</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A box contains 15 transistors, 3 of which are defective. If 3 are selected at&#8203; random, find the probability that...<BR>\n" );
document.write( "a. All are defective.<BR>\n" );
document.write( "b. None are defective. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #654700 by </B><A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><B>jim_thompson5910(35256)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=654700\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <font color=black size=3><BR>\n" );
document.write( "Part a)\r<BR>\n" );
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document.write( "There is only one way to select a batch of 3 transistors where they're all defective. \r<BR>\n" );
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document.write( "There are 15 C 3 = (15!)/(3!*(15-3)!) = 455 ways to select 3 resistors. This is where we don't care if they work or not. \r<BR>\n" );
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document.write( "The notation 15 C 3 refers to the <a  rel=nofollow HREF=\"http://www.mathwords.com/c/combination_formula.htm\">combination formula</a>\r<BR>\n" );
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document.write( "Dividing the two values gives 1/455 = 0.0021978021978. When we round to 3 decimal places, we get 0.002\r<BR>\n" );
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document.write( "Part b)\r<BR>\n" );
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document.write( "There are 15-3 = 12 non-defective transistors. There are 12 C 3 = (12!)/(3!*(12-3)!) = 220 ways to pick 3 transistors where none of them are defective.\r<BR>\n" );
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document.write( "This is still out of the same total of 455 different combos (found earlier in part a)\r<BR>\n" );
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document.write( "220/455 = 0.48351648351649 which rounds to 0.484 (assuming your book wants you to round to 3 decimal places)\r<BR>\n" );
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document.write( "Summary:<BR>\n" );
document.write( "Answer to part a): <font color=red>0.002</font><BR>\n" );
document.write( "Answer to part b): <font color=red>0.484</font>\r<BR>\n" );
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document.write( "Answers are approximate. The values are rounded to 3 decimal places.  <BR>\n" );
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