document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=206208>Question 206208</A>: <I><SPAN STYLE=\"word-break: break-all;\"> In a shop there are 20 customers, 18 of whom will make a purchase. If three customers are selected, one at a time, at random, what is the probability that all will make a purchase?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #155760 by </B><A HREF=/tutors/aboutme.mpl?userid=Marth><B>Marth(57)</B></A><img src=\"/images/stars/stars-08.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Marth><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=155760\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> This is the same as selecting 3 customers without replacement and finding the probability that each one will make a purchase.\r<BR>\n" );
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document.write( "The probability of the 1st customer making a purchase is <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=18%2F20 ALIGN=MIDDLE  ALT=\"18%2F20\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "But for the 2nd customer, after having selected the 1st customer without replacement, the probability is <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=17%2F19 ALIGN=MIDDLE  ALT=\"17%2F19\"   DISABLED_style= \"max-width:90%; height:auto;\" > because you remove one customer that has made a purchase.<BR>\n" );
document.write( "Do the same for the 3rd customer: <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=16%2F18 ALIGN=MIDDLE  ALT=\"16%2F18\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "Now multiply them together: <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%2818%2F20%29%2A%2817%2F19%29%2A%2816%2F18%29 ALIGN=MIDDLE  ALT=\"%2818%2F20%29%2A%2817%2F19%29%2A%2816%2F18%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=68%2F95 ALIGN=MIDDLE  ALT=\"68%2F95\"   DISABLED_style= \"max-width:90%; height:auto;\" > </SPAN>\n" );
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