document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=916972>Question 916972</A>: <I><SPAN STYLE=\"word-break: break-all;\"> a tank fitted with two pipes is to be filled with water. One pipe can fill it in 15 hours. After it has been open for 3 hours, the second pipe is opened and the tank is filled in 4 hours more. How long would it take the second pipe alone to fill the tank </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #556441 by </B><A HREF=/tutors/aboutme.mpl?userid=mananth><B>mananth(16946)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=mananth><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=mananth><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=556441\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> a tank fitted with two pipes is to be filled with water. One pipe can fill it in 15 hours. After it has been open for 3 hours, the second pipe is opened and the tank is filled in 4 hours more. How long would it take the second pipe alone to fill the tank\r<BR>\n" );
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document.write( " One pipe can fill it in 15 hours.\r<BR>\n" );
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document.write( "it does 1/15 of the job in 1 hour\r<BR>\n" );
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document.write( " After it has been open for 3 hours,<BR>\n" );
document.write( "In 3 hours it does 3/15 of the job\r<BR>\n" );
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document.write( "Balance job = 1-3/15\r<BR>\n" );
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document.write( "=12/15 of the job\r<BR>\n" );
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document.write( " the second pipe is opened and the tank is filled in 4 hours more.\r<BR>\n" );
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document.write( "12/15 of the job they do in 4 hours\r<BR>\n" );
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document.write( "1 job they do in 4/(12/15)\r<BR>\n" );
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document.write( "=5 hours\r<BR>\n" );
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document.write( "let second pipe take x hours to fill the tank<BR>\n" );
document.write( "it does 1/x of the job in 1 hour<BR>\n" );
document.write( "First pipe does 1/15 of the job in 1 hour\r<BR>\n" );
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document.write( "together they do 1/5 of the job in 1 hour\r<BR>\n" );
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document.write( "1/15 +1/x = 1/5\r<BR>\n" );
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document.write( "1/5 -1/15 =1/x\r<BR>\n" );
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document.write( "2/15 = 1/x\r<BR>\n" );
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document.write( "x= 15/2<BR>\n" );
document.write( "=7.5 hours\r<BR>\n" );
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document.write( " the second pipe alone to fill the tank will take 7.5 hours </SPAN>\n" );
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