document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=99847>Question 99847</A>: <I><SPAN STYLE=\"word-break: break-all;\"> We cannot get the correct answer to this probability question: A bag contains red & blue marbles. you pick 2 marbles at random without replacing the first one. The probability of drawing a blue and then a red is 4/15. The probability that your second marble is red if your first is blue is 2/3. Find the probability the first marble is blue.  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #72673 by </B><A HREF=/tutors/aboutme.mpl?userid=edjones><B>edjones(8007)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=edjones><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=edjones><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=72673\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Since the probability of a red ball is 2/3 after a blue one was picked 2/3 of the balls in the bag are red.<BR>\n" );
document.write( "2/3,4/6,6/9,8/15<BR>\n" );
document.write( "before the 1st ball was drawn the probability of drawing a red was<BR>\n" );
document.write( "2/4,4/7,6/10,8/16<BR>\n" );
document.write( "8/16*8/15=64//240=4/15 eureka!<BR>\n" );
document.write( "so the probability that the 1st ball is blue = 8/16 or 1/2<BR>\n" );
document.write( "Ed </SPAN>\n" );
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