document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=727248>Question 727248</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A box contains 20 blocks. Fifteen of the blocks are red, the rest are green. If six blocks are selected at random, how many ways can six red blocks be selected?\r<BR>\n" );
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document.write( "I have tried 20P6 but I am not sure that is the right formula to be using. I figure some sort of probability of red vs. green needs to be included. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #445025 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=445025\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Order does NOT matter, so you do NOT use n P r (permutation), you use n C r (combination)\r<BR>\n" );
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document.write( "So there are 15 C 6 = 5005 distinct ways to pick 6 red blocks\r<BR>\n" );
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document.write( "This is out of 20 C 6 = 38760 ways total (to pick any color block and pick 6 of them)\r<BR>\n" );
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document.write( "So the probability of picking 6 red blocks is\r<BR>\n" );
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document.write( "P(6 red blocks) = (# of ways to pick 6 red blocks)/(# of ways to pick 6 blocks)\r<BR>\n" );
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document.write( "P(6 red blocks) = (15 C 6)/(20 C 6)\r<BR>\n" );
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document.write( "P(6 red blocks) = (5005)/(38760)\r<BR>\n" );
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document.write( "P(6 red blocks) = <font color=\"red\">0.12912796697627</font> </SPAN>\n" );
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