document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1085997>Question 1085997</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Two boats travel in a river having a current of 5 km/hr. The boat going upstream had departed 1 hr before the boat going downstream. A period of time after the boat going downstream had departed, a radio conversation between the boats indicated that one boat was 44 km upstream and the other was 75 km downstream. Approximately, to the nearest tenth of a kilometer per hour, the speed of each boat in still water.\r<BR>\n" );
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document.write( "Find the speed of the boats in still water. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #700180 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><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=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=700180\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Two boats travel in a river having a current of 5 km/hr.<BR>\n" );
document.write( " The boat going upstream had departed 1 hr before the boat going downstream.<BR>\n" );
document.write( " A period of time after the boat going downstream had departed, a radio conversation between the boats indicated that one boat was 44 km upstream and the other was 75 km downstream.<BR>\n" );
document.write( " Approximately, to the nearest tenth of a kilometer per hour, the speed of each boat. <BR>\n" );
document.write( " Find the speed of the boats in still water. <BR>\n" );
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document.write( "In order to do this problem you have to assume the boats have the same speed in still water<BR>\n" );
document.write( "let s = the their still water speed<BR>\n" );
document.write( "then<BR>\n" );
document.write( "(s+5) = effective speed of boat1 going downstream<BR>\n" );
document.write( "and<BR>\n" );
document.write( "(s-5) = effective speed of  boat2 going upstream<BR>\n" );
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document.write( "Write a time equation; time = dist/speed (their travel times differ by 1 hr)<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=44%2F%28%28s-5%29%29 ALIGN=MIDDLE  ALT=\"44%2F%28%28s-5%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > - <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=75%2F%28%28s%2B5%29%29 ALIGN=MIDDLE  ALT=\"75%2F%28%28s%2B5%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 1 hr<BR>\n" );
document.write( "multiply by (s-5)(s+5), cancel the denominators<BR>\n" );
document.write( "44(s+5) - 75(s-5) = (s+5)(s-5)<BR>\n" );
document.write( "44s + 220 - 75s + 375 = s^2 - 25<BR>\n" );
document.write( "-31s + 595 = s^2 - 25<BR>\n" );
document.write( "Arrange as a quadratic equation<BR>\n" );
document.write( "0 = s^2 + 31s - 25 - 595<BR>\n" );
document.write( "s^2 + 31s - 620 = 0<BR>\n" );
document.write( "Using the quadratic formula, I got a positive solution of <BR>\n" );
document.write( "s = 13.83 km/hr in still water<BR>\n" );
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document.write( "Check this find the actual time of boat1<BR>\n" );
document.write( "75/18.83 ~ 4 hrs<BR>\n" );
document.write( "find the time boat2<BR>\n" );
document.write( "44/8.83 ~ 5 hrs, one hour difference <BR>\n" );
document.write( " \r<BR>\n" );
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document.write( " </SPAN>\n" );
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