document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1081622>Question 1081622</A>: <I><SPAN STYLE=\"word-break: break-all;\"> URN 1 contains 4 red balls and 3 black balls. URN 2 contains 5 red balls and 3 black balls. URN 3 contains 2 red and 3 black. If an urn is selected at random and a ball is drawn, find the probability that it will be red. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #695685 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=695685\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> P(urn 1)=(1/3) and probability urn 1 and red ball is (4/7)(1/3)=(4/21)<BR>\n" );
document.write( "P(urn 2)=(1/3) and probability urn 2 and red ball is (5/8)(1/3)=(5/24)<BR>\n" );
document.write( "P(urn 3)=(1/3) and probability urn 3 and red ball is (2/5)(1/3)=(2/15)<BR>\n" );
document.write( "The sum of those probabilities has common denominator 21*15*24<BR>\n" );
document.write( "numerator is 4*(15*24)+5(21*15)+2(21*24)/(21*15*24)<BR>\n" );
document.write( "numerator is 1440+1575+1008=4023<BR>\n" );
document.write( "denominator is 7560<BR>\n" );
document.write( "probability is 0.5321 ANSWER<BR>\n" );
document.write( "by adding 4/21(0.190) and 5/24 (0.208) and 2/15(0.133), one gets 0.531, but there is rounding error.<BR>\n" );
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