document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=413815>Question 413815</A>: <I><SPAN STYLE=\"word-break: break-all;\"> An oil tanker can be emptied by the main pump in 4 hours. An auxiliary pump can empty the tanker in 7 hours. If the main pump is started at 7 pm, when should the auxiliary pump be started so that the tanker is emptied by 10 pm? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #290317 by </B><A HREF=/tutors/aboutme.mpl?userid=josmiceli><B>josmiceli(19441)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josmiceli><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=josmiceli><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=290317\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The tanker is to be emptied in 2 stages in 3 hrs.<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t ALIGN=MIDDLE  ALT=\"t\"   DISABLED_style= \"max-width:90%; height:auto;\" > = hours that main pump alone is working<BR>\n" );
document.write( "Amount pumped by main pump = <BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%281%2F4%29%2At+=+t%2F4 ALIGN=MIDDLE  ALT=\"%281%2F4%29%2At+=+t%2F4\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "That is: (1 tank)/(4 hrs) x (t hrs)<BR>\n" );
document.write( "The auxilliary pump + main pump will then pump out:<BR>\n" );
document.write( "(2)<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%281%2F4%29%2A%283+-+t%29+%2B+%281%2F7%29%2A%283+-+t%29 ALIGN=MIDDLE  ALT=\"%281%2F4%29%2A%283+-+t%29+%2B+%281%2F7%29%2A%283+-+t%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "If I add (1) and (2), I should get <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1 ALIGN=MIDDLE  ALT=\"1\"   DISABLED_style= \"max-width:90%; height:auto;\" > (1 tank pumped)<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t%2F4+%2B+%283+-+t%29%2F4+%2B+%283+-+t%29%2F7+=+1 ALIGN=MIDDLE  ALT=\"t%2F4+%2B+%283+-+t%29%2F4+%2B+%283+-+t%29%2F7+=+1\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Multiply both sides by <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=4%2A7 ALIGN=MIDDLE  ALT=\"4%2A7\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=7t+%2B+7%2A%283+-+t%29+%2B+4%2A%283+-+t%29++=+28 ALIGN=MIDDLE  ALT=\"7t+%2B+7%2A%283+-+t%29+%2B+4%2A%283+-+t%29++=+28\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=7t+%2B+%283+-+t%29%2A11+=+28 ALIGN=MIDDLE  ALT=\"7t+%2B+%283+-+t%29%2A11+=+28\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=7t+%2B+33+-+11t+=+28 ALIGN=MIDDLE  ALT=\"7t+%2B+33+-+11t+=+28\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=4t+=+5 ALIGN=MIDDLE  ALT=\"4t+=+5\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t+=+5%2F4 ALIGN=MIDDLE  ALT=\"t+=+5%2F4\"   DISABLED_style= \"max-width:90%; height:auto;\" > hrs<BR>\n" );
document.write( "So, the main pump runs alone for 1 hr 15 min. That means<BR>\n" );
document.write( "the auxilliary pump comes on at 8:15<BR>\n" );
document.write( "check answer:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t%2F4+%2B+%283+-+t%29%2F4+%2B+%283+-+t%29%2F7+=+1 ALIGN=MIDDLE  ALT=\"t%2F4+%2B+%283+-+t%29%2F4+%2B+%283+-+t%29%2F7+=+1\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%285%2F4%29%2F4+%2B+%283+-+%285%2F4%29%29%2F4+%2B+%283+-+%285%2F4%29%29%2F7+=+1 ALIGN=MIDDLE  ALT=\"%285%2F4%29%2F4+%2B+%283+-+%285%2F4%29%29%2F4+%2B+%283+-+%285%2F4%29%29%2F7+=+1\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5%2F16+%2B+7%2F16+%2B+4%2F16+=+1 ALIGN=MIDDLE  ALT=\"5%2F16+%2B+7%2F16+%2B+4%2F16+=+1\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+1+=+1 ALIGN=MIDDLE  ALT=\"+1+=+1\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "OK\r<BR>\n" );
document.write( "\n" );
document.write( "  </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );