document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=939002>Question 939002</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 15. There are 20 children in the cast of a class play, and 8 of the<BR>\n" );
document.write( "children are boys. Of the boys, 4 have a speaking part in the<BR>\n" );
document.write( "play, and of the girls, 8 do not have a speaking part in the<BR>\n" );
document.write( "play. If a child from the cast of the play is chosen at random,<BR>\n" );
document.write( "what is the probability that the child has a speaking part? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #572133 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=572133\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\">   <BR>\n" );
document.write( "It all looks confusing when we try to juggle with all those numbers in the head.  The problem can be solved systematically by constructing a contingency table.<BR>\n" );
document.write( "  <BR>\n" );
document.write( "role/gender B G total<BR>\n" );
document.write( "speaking...... 4 4 8<BR>\n" );
document.write( "silent............ 4 8 12<BR>\n" );
document.write( "total............. 8 12 20\r<BR>\n" );
document.write( "\n" );
document.write( "Probability of a child having a speaking part is therefore <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%284%2B4%29%2F20=8%2F20=2%2F5 ALIGN=MIDDLE  ALT=\"%284%2B4%29%2F20=8%2F20=2%2F5\"   DISABLED_style= \"max-width:90%; height:auto;\" > </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );