document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=830306>Question 830306</A>: <I><SPAN STYLE=\"word-break: break-all;\"> in how many ways can 9 friends be formed into groups of 4 persons to play cards?\r<BR>\n" );
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document.write( "at first i thought it's just 9C4. then i realized another group of 4 can be made out of 5 left persons, leaving one behind. so the answer must be (9C4)(5C4) ways...? i really don't know, please help meeeh~ </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #500528 by </B><A HREF=/tutors/aboutme.mpl?userid=rothauserc><B>rothauserc(4718)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=rothauserc><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=rothauserc><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=500528\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> this is a combination problem because order does not matter, that is, set (1,2,3,4) is the same as set (2,3,4,1)<BR>\n" );
document.write( "the total number of combinations can be calculated from the following formula<BR>\n" );
document.write( "C =   n! / (r! * (n - r)!)  where n is the number of things to choose from and you choose r of them, therefore <BR>\n" );
document.write( "C = 9! / (4! * (9 - 4)!<BR>\n" );
document.write( "C = 9! / (4! * 5!)<BR>\n" );
document.write( "C = 9*8*7*6 / 4*3*2*1 = 9*7*2 / 1 = 9*7*2 = 126 combinations </SPAN>\n" );
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