document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=436132>Question 436132</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Word problem.\r<BR>\n" );
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document.write( "It takes 60 minutes to fill a pond with water alone.<BR>\n" );
document.write( "It takes 80 minutes to drain a pond of water alone.\r<BR>\n" );
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document.write( "How long will it take to fill the pond while it is being drained at the same time? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #853275 by </B><A HREF=/tutors/aboutme.mpl?userid=ikleyn><B>ikleyn(53570)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ikleyn><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=ikleyn><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=853275\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .<BR>\n" );
document.write( "Word problem.\r<BR>\n" );
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document.write( "It takes 60 minutes to fill a pond with water alone.<BR>\n" );
document.write( "It takes 80 minutes to drain a pond of water alone.\r<BR>\n" );
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document.write( "How long will it take to fill the pond while it is being drained at the same time?<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The solution in the post by @mananth is &nbsp;FATALLY &nbsp;WRONG &nbsp;due to elementary arithmetic error.\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;I came to bring a correct solution.\r<BR>\n" );
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document.write( "consider filling or emptying the pool as 1 job.\r<BR>\n" );
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document.write( "emptying the pool = 80 minutes<BR>\n" );
document.write( "so 1/80 of the job is done in 1 minute<BR>\n" );
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document.write( "Filling time = 60 minutes<BR>\n" );
document.write( "1/60 of the job in 1 minute<BR>\n" );
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document.write( "difference = 1/60 -1/80<BR>\n" );
document.write( "(80-60)/80*60<BR>\n" );
document.write( "20/4800<BR>\n" );
document.write( "1/240 of the job is done in 1 minute when both are on.\r<BR>\n" );
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document.write( "so it will take 240 minutes = 4 hours to fill the pool.\r<BR>\n" );
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document.write( "Solved correctly.\r<BR>\n" );
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document.write( "It can be seen even with unarmed eye, using common sense - ONLY.\r<BR>\n" );
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document.write( "The filling hose fills the tank in 1 hour - but then the drain takes out 3/4 of the water <BR>\n" );
document.write( "from the tank during this 1 hour,<BR>\n" );
document.write( "so only 1/4 of the tank is filled in one hour.\r<BR>\n" );
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document.write( "Hence, 4 hours are needed.\r<BR>\n" );
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document.write( " </SPAN>\n" );
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