document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1022435>Question 1022435</A>: <I><SPAN STYLE=\"word-break: break-all;\"> In how many ways can a doubles game of tennis be arranged from eleven boys and seven girls if each side must have one boy and one girl?<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #638136 by </B><A HREF=/tutors/aboutme.mpl?userid=mathmate><B>mathmate(429)</B></A><img src=\"/images/stars/stars-10.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=mathmate><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=mathmate><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=638136\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\">  <BR>\n" );
document.write( "Question:<BR>\n" );
document.write( "In how many ways can a doubles game of tennis be arranged from eleven boys and seven girls if each side must have one boy and one girl?<BR>\n" );
document.write( " <BR>\n" );
document.write( "Solution:<BR>\n" );
document.write( "It should be understood that order does not count here, so it is a question of combination.<BR>\n" );
document.write( "For each match, we need two boys and two girls.<BR>\n" );
document.write( "The number of ways this can be done is C(11,2)*C(7,2)=55*21=1155<BR>\n" );
document.write( "where C(n,r)=n!/(r!(n-r)!) is the binomial coefficient.<BR>\n" );
document.write( " <BR>\n" );
document.write( "Moreover, given two boys and two girls, there are two arrangements of opponents, i.e. a particular girl can choose one of the two boys as partner.<BR>\n" );
document.write( " <BR>\n" );
document.write( "Therefore the total number of different matches is 1155*2=2310. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );