document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1209017>Question 1209017</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A bathroom tub will fill in 15 minutes with both faucets open and the stopper in place. With both faucets closed and the stopper removed, the tub will empty in 20 minutes. How long will it take for the tub to fill if both faucets are open and the stopper is removed? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #847590 by </B><A HREF=/tutors/aboutme.mpl?userid=greenestamps><B>greenestamps(13196)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=greenestamps><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=greenestamps><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=847590\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "The response from tutor @ikleyn shows a standard formal algebraic solution and a quick mental solution.  While you might require a formal algebraic solution, you should not ignore the fact that solving problems like this mentally is excellent brain exercise.<br><BR>\n" );
document.write( "Here is solution by another method that can be done mentally and quickly.  This method can be used to solve many similar \"working together\" problems.<br><BR>\n" );
document.write( "Consider the least common multiple of the two given times.  The two faucets can fill the tub in 15 minutes; the drain can empty the tub in 20 minutes.  The least common multiple of those two times is 60 minutes<br><BR>\n" );
document.write( "Now consider what the faucets and drain could accomplish in 60 minutes.<br><BR>\n" );
document.write( "The faucets could fill the tub 60/15 = 4 times; the drain could empty the tub 60/20 = 3 times.<br><BR>\n" );
document.write( "So in 60 minutes with the faucets and drain both operating, the overall result would be filling the tub 4-3 = 1 time.<br><BR>\n" );
document.write( "So the time to fill the tube with both faucets and the drain both operating is 60 minutes, or 1 hour.<br><BR>\n" );
document.write( "ANSWER: 1 hour<br><BR>\n" );
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