document.write( "Question 1057506: The current in a stream moves at a speed of 7 mph. A boat travels 38 mi upstream and 38 mi downstream in a total time of 3 hr. What is the speed of the boat in still water?\r
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Algebra.Com's Answer #672541 by ikleyn(52811) $\"\"$ $\"About$

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\n" ); document.write( "The current in a stream moves at a speed of 7 mph. A boat travels 38 mi upstream and 38 mi downstream in a total time of 3 hr.
\n" ); document.write( "What is the speed of the boat in still water?
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document.write( "Let \"u\" be the speed of the boat in still water.\r\n" );
document.write( "Then the boat speed moving downstream is (u+7) mph,\r\n" );
document.write( "while the speed moving upstream is (u-7).\r\n" );
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document.write( "The time traveling upstream is    hours.\r\n" );
document.write( "The time traveling downstream is    hours.\r\n" );
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document.write( "The total time for the round trip is   +  hours.\r\n" );
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document.write( "And the equation is \r\n" );
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document.write( " +  = 3.    (\"time\" equation).\r\n" );
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document.write( "To solve it, multiply both sides by (u-7)*(u+7).\r\n" );
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document.write( "You will get\r\n" );
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document.write( "38*(u+7) + 38*(u-7) = .\r\n" );
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document.write( "Simplify:\r\n" );
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document.write( " = ,\r\n" );
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document.write( " = 0.\r\n" );
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document.write( "Solve using the quadratic formula\r\n" );
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document.write( " =  = .\r\n" );
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document.write( "We are interested in positive root only.\r\n" );
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document.write( "It is u =  =~ 13.569 km/h (approximately).\r\n" );
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document.write( "Check.   +  = 3.000 hours.\r\n" );
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document.write( "Answer.  The boat speed in still water is 13.569 km/h (approximately).\r\n" );
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\n" ); document.write( "\n" ); document.write( "It is a typical Upstream and Downstream round trips word problem.\r
\n" ); document.write( "\n" ); document.write( "You can find similar fully solved problems on upstream and downstream round trips with detailed solutions in the 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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