document.write( "Question 1074633: The speed of a boat in still water is 9 km/h. The boat travels 72 km upstream and 72 km downstream in a total time of 18 hr. What is the speed of the stream? \n" ); document.write( "

Algebra.Com's Answer #689303 by ikleyn(52786) $\"\"$ $\"About$

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document.write( "Let V be the speed of the stream (of the current), in km/h\r\n" );
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document.write( "Then   the speed of the boat traveling downstream is (9+v) km/h, \r\n" );
document.write( "while  the speed of the boat traveling upstream   is (9-v) km/h.\r\n" );
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document.write( "The time for traveling upstream is  hours,\r\n" );
document.write( "while The time for traveling downstream is  hours.\r\n" );
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document.write( "Therefore, the time equation is \r\n" );
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document.write( " = 18   (total time).\r\n" );
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document.write( "Divide both sides by 18 and multiply both sides by (9-v)*(9+v). You will get\r\n" );
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document.write( "4(9+v) + 4*(9-v) = ,   or\r\n" );
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document.write( " = 81 - 2*36 = 9.\r\n" );
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document.write( "Therefore, v = 3 km/h is the rate of the current.\r\n" );
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document.write( "Answer.  The rate of the current is 3 km/h.\r\n" );
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\n" ); document.write( "\n" ); document.write( "It is a typical and standard Upstream and Downstream round trip word problem.\r
\n" ); document.write( "\n" ); document.write( "You can find many similar fully solved problems on upstream and downstream round trips with detailed solutions in lessons \r
\n" ); document.write( "\n" ); document.write( "    - Wind and Current problems \r
\n" ); document.write( "\n" ); document.write( "    - More problems on upstream and downstream round trips \r
\n" ); document.write( "\n" ); document.write( "    - Selected problems from the archive on the boat floating Upstream and Downstream \r
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\n" ); document.write( "\n" ); document.write( "Read them attentively and learn how to solve this type of problems once and for all.\r
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\n" ); document.write( "\n" ); document.write( "Also, you have this free of charge online textbook in ALGEBRA-I in this site\r
\n" ); document.write( "\n" ); document.write( "    - ALGEBRA-I - YOUR ONLINE TEXTBOOK.\r
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\n" ); document.write( "\n" ); document.write( "The referred lessons are the part of this textbook under the section \"Word problems\", the topic \"Travel and Distance problems\".\r
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