document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=515481>Question 515481</A>: <I><SPAN STYLE=\"word-break: break-all;\"> BOATING TRIP: Cesar starts out on a boating trip at 8 am. Cesar's boat can go 20 miles per hour in still water. How far downsream can Cesar go if the current is 5 miles per hour and he wishes to go down and back in 4 hours? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #344000 by </B><A HREF=/tutors/aboutme.mpl?userid=oberobic><B>oberobic(2304)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=oberobic><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=344000\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> d = r*t is the basic distance equation.<BR>\n" );
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document.write( "r = 20 mph in still water<BR>\n" );
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document.write( "c = 5 mph is the current in the river<BR>\n" );
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document.write( "going upstream, the speed = r-c = 20-5 = 15<BR>\n" );
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document.write( "going downstream, the speed = r+c = 25<BR>\n" );
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document.write( "d = d each way (that is, he returns to the same point he started).<BR>\n" );
document.write( "The roundtrip = 2d.<BR>\n" );
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document.write( "d/r = t<BR>\n" );
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document.write( "he wants to make the whole trip in 4 hr<BR>\n" );
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document.write( "d/15 + d/25 = 4 hr<BR>\n" );
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document.write( "(25d + 15d) / (15*25) = 4<BR>\n" );
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document.write( "cross multiply<BR>\n" );
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document.write( "40d = 4*15*25<BR>\n" );
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document.write( "d = 4*15*25/40<BR>\n" );
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document.write( "d = 75/2 = 37 1/2 miles<BR>\n" );
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document.write( "Always check your answer.<BR>\n" );
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document.write( "In this case, what can we check?<BR>\n" );
document.write( "Time.<BR>\n" );
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document.write( "37.5 miles/ 15 mph = 2.5 hr going upstream (against the current)<BR>\n" );
document.write( "37.5 miles/ 25 mph = 1.5 hr going downstream (with the current)<BR>\n" );
document.write( "2.5+1.5= 4 hr<BR>\n" );
document.write( "Correct.<BR>\n" );
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document.write( "Done. </SPAN>\n" );
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