document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1105388>Question 1105388</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Certain class contains 60% of boys and 40% of girls, all aged between 17 and 27 years. It is known that 80% of young people of both sexes are under 21 years of age and that among girls, 10% are over 21 years.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "a) a person is chosen and it is verified that he is under 21 years. What is the probability of being a girl?<BR>\n" );
document.write( "b) a person is chosen at random. What is the probability of being a boy under the age of 21?<BR>\n" );
document.write( "c) choose a boy at random. How likely is he to be less than 21 years old? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #720213 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=720213\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Use 1000.<BR>\n" );
document.write( "=====B===========G========total<BR>\n" );
document.write( "<21--- 440----------360========800<BR>\n" );
document.write( ">21----160------------40========200<BR>\n" );
document.write( "Total--600-----------400---------1000\r<BR>\n" );
document.write( "\n" );
document.write( "a. <21 is 0.45 probability of being a girl.<BR>\n" );
document.write( "b. 0.44 probability of being a boy under 21<BR>\n" );
document.write( "c. Boy less than 21 is 0.73 probability, given that a boy is chosen. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );