document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=253212>Question 253212</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A water tank has an inlet pipe and a drain pipe. A full tank can be emptied in 30 minutes if the drain is opened and empty tank can be filled in 45 minutess with the inlet pipe opened.  If both pipes are accidently opened when the tank is full, then how long would it take to empty the tank?\r<BR>\n" );
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document.write( "I believe this is a trick question and can possible be unknown. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #185450 by </B><A HREF=/tutors/aboutme.mpl?userid=Greenfinch><B>Greenfinch(383)</B></A><img src=\"/images/stars/stars-10.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Greenfinch><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=Greenfinch><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=185450\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Tank is full = 1<BR>\n" );
document.write( "Tank is empty = 0<BR>\n" );
document.write( "Rate of filling is t/30<BR>\n" );
document.write( "Rate of emptying is t/45<BR>\n" );
document.write( "The condition is therefore 1-(t/30) + (t/45) = 0<BR>\n" );
document.write( "LCM is 90 so 90/90 -(3t - 2t)/90 = 0<BR>\n" );
document.write( "or 90 -(3t - 2t)=0<BR>\n" );
document.write( "90 -t = 0<BR>\n" );
document.write( "t = 90 (minutes)<BR>\n" );
document.write( "The problem gets more difficult if the rate of emptying depends on the level of water left in the tank, but this is not the case here. </SPAN>\n" );
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