document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=477221>Question 477221</A>: <I><SPAN STYLE=\"word-break: break-all;\"> please help me solve this question... a pool has two pumps. Pump A empties the pool in 4 hours. Pump B empties the pool in 12 hours. How long will it take to empty the pool if both pumps are working together? thanks so much\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "i think the answer is 3?...i divided 3 into 12..not sure if thats correct </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #327125 by </B><A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><B>jim_thompson5910(35256)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=327125\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Rate of pump A: 1/4 of a pool per hour\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Rate of pump B: 1/12 of a pool per hour\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Combined rate: 1/4+1/12 = 3/12+1/12 = 4/12 = 1/3\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "So if they work together, the two pumps have a combined rate of 1/3 of a pool per hour (ie in one hour, the two pumps will empty 1/3 of the pool)\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "But we want to empty ONE pool (not 1/3 of one). So we need to multiply 1/3 by some number x to get 1. So \r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%281%2F3%29x=1 ALIGN=MIDDLE  ALT=\"%281%2F3%29x=1\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Now solve for x\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%281%2F3%29x=1 ALIGN=MIDDLE  ALT=\"%281%2F3%29x=1\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x=1%2A3 ALIGN=MIDDLE  ALT=\"x=1%2A3\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x=3 ALIGN=MIDDLE  ALT=\"x=3\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "So it will take the two pumps 3 hours to empty the pool. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );