document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=247835>Question 247835</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A computer dealer had 20 computers of which 3 are defective.<BR>\n" );
document.write( "A. If she selects a computer at random what is the probability that it is defective?<BR>\n" );
document.write( "B. If she selects computers at random, what is the probability that one of them is defective?<BR>\n" );
document.write( "C. If she selects 3 computers at random what is the probability that all of them 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 #180668 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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=180668\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A computer dealer had 20 computers of which 3 are defective.<BR>\n" );
document.write( "Binomial with n=20 ; p=3/20 ; x varies<BR>\n" );
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document.write( "A. If she selects a computer at random what is the probability that it is defective?<BR>\n" );
document.write( "P(one selected defective) = 3/20<BR>\n" );
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document.write( "B. If she selects computers at random, what is the probability that one of them is defective?<BR>\n" );
document.write( "That depends on how many computers she selects.<BR>\n" );
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document.write( "C. If she selects 3 computers at random what is the probability that all of them are defective?<BR>\n" );
document.write( "P(all of 3 are defective) <BR>\n" );
document.write( "# of ways to select 3 defective: 1<BR>\n" );
document.write( "# of ways to select 3 without restriction: 20C3 = 1140<BR>\n" );
document.write( "P(3 of 3 are defective) = 1/1140<BR>\n" );
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document.write( "Another way to work this is:<BR>\n" );
document.write( "(3/20)(2/19)(1/18) = 1/1140<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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document.write( " </SPAN>\n" );
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