document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=54260>Question 54260</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Could someone please help me with this probability and statistics problem?\r<BR>\n" );
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document.write( "Prove both algebraically and combinatorially (in terms of selections) that <BR>\n" );
document.write( "if n1 + n2 + n3 then (n choose n1) =  (n choose n1) (n-n1 choose n2)<BR>\n" );
document.write( "It's hard to write out the form of (n choose n1) in plain text basically<BR>\n" );
document.write( "(n choose n1) equals to <BR>\n" );
document.write( "(    n     )<BR>\n" );
document.write( "(n1, n2, n3). Same for <BR>\n" );
document.write( "(n-n1)<BR>\n" );
document.write( "( n2 )\r<BR>\n" );
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document.write( "Thank you so much in advance to anyone who can help on this problem. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #37133 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=37133\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Maybe it's the notation that is confusing but<BR>\n" );
document.write( "your problem makes no sense to me.<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H.\r<BR>\n" );
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