document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=6864>Question 6864</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I am stuck on a question from my text book, on Inequalities, Permutations, and Probibility.  Can someone help me?    My question is....A teacher has a set of 12 problems to use on a math exam.  The teacher makes different versions of the exam by putting 10 questions on each exam.  How many different exams can the teacher make.  I am not sure how to set up this problem. I keep multiplying 10 and 12 but I don't think that is right. Can someone help me.  My paper is due tomorrow. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #3775 by </B><A HREF=/tutors/aboutme.mpl?userid=longjonsilver><B>longjonsilver(2297)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=longjonsilver><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/cgi-bin/show-face.mpl?user=longjonsilver><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=3775\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> i often get stuck on permutations and combinations myself, so i always end up going to first principles by thinking of an easier solution.\r<BR>\n" );
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document.write( "Got to remember that both perms and combos use factorials either straightforward factorials or factorials divided by factorials, so how about having 4 questions and picking 3? How many? answer is ABC, ABD, ACD, BCD -->4.\r<BR>\n" );
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document.write( "So, 4 questions is 4! --> 120. Now we need to make this smaller, by division: dividing by 3! would give an answer of 4.\r<BR>\n" );
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document.write( "4 questions: pick 1 is 4 possible combinations, 4!/3!. Actually, by thinking about 1 question from 4 or 2 from 4, the actual calc is 4!/(3!1!).\r<BR>\n" );
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document.write( "so, your question is 12!/(10!2!) = 66... basically:\r<BR>\n" );
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document.write( "1234567890<BR>\n" );
document.write( "123456789A<BR>\n" );
document.write( "123456789B\r<BR>\n" );
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document.write( "123456780A<BR>\n" );
document.write( "123456780B<BR>\n" );
document.write( "etc etc\r<BR>\n" );
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document.write( "Hope this makes sense.\r<BR>\n" );
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document.write( "jon.<BR>\n" );
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