document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=628799>Question 628799</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A motorboat maintain a constant speed of 15 mph in the water in going 10 miles upstream and then returning. The total time for the trip was 1.5 hours. Find the speed of the water current?\r<BR>\n" );
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document.write( "please solve this .. urgently </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #395935 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=395935\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A motorboat maintain a constant speed of 15 mph in the water in going 10 miles<BR>\n" );
document.write( " upstream and then returning.<BR>\n" );
document.write( " The total time for the trip was 1.5 hours.<BR>\n" );
document.write( " Find the speed of the water current?<BR>\n" );
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document.write( "Let c = speed of the current<BR>\n" );
document.write( "then<BR>\n" );
document.write( "(15-c) = effective speed upstream<BR>\n" );
document.write( "and<BR>\n" );
document.write( "(15+c) = effective speed downstream<BR>\n" );
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document.write( "Write a time equation, time = dist/speed<BR>\n" );
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document.write( "time up + time back = 1.5 hrs<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=10%2F%28%2815-c%29%29 ALIGN=MIDDLE  ALT=\"10%2F%28%2815-c%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > + <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=10%2F%28%2815%2Bc%29%29 ALIGN=MIDDLE  ALT=\"10%2F%28%2815%2Bc%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 1.5<BR>\n" );
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document.write( "Multiply thru by (15-c)(15+c) to clear the denominators, results:<BR>\n" );
document.write( "10(15+c) + 10(15-c) = 1.5(15+c)(15-c)<BR>\n" );
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document.write( "150 + 10c + 150 - 10c = 1.5(225-c^2)<BR>\n" );
document.write( "300 = 337.5 - 1.5c^2<BR>\n" );
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document.write( "Add 1.5c^2 to both sides, subtract 300 from both sides<BR>\n" );
document.write( "1.5c^2 = 337.5 - 300<BR>\n" );
document.write( "1.5c^2 = 37.5<BR>\n" );
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document.write( "Divide both sides by 1.5<BR>\n" );
document.write( "c^2 = 25<BR>\n" );
document.write( "c = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sqrt%2825%29 ALIGN=MIDDLE  ALT=\"sqrt%2825%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "c = 5 mph is the current<BR>\n" );
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document.write( "You can check this in the original time equation; replace with 5  </SPAN>\n" );
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