document.write( "Question 1055307: The current of a river is 4 miles per hour. A boat travels to a point 48 miles upstream and back in 5 hours. What is the speed of the boat in still water? \n" ); document.write( "

Algebra.Com's Answer #670539 by ikleyn(52781) $\"\"$ $\"About$

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\n" ); document.write( "The current of a river is 4 miles per hour. A boat travels to a point 48 miles upstream and back in 5 hours. What is the speed of the boat in still water?
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document.write( "Your equation is\r\n" );
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document.write( " = 5.\r\n" );
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document.write( "Here u is the unknown speed of the boat in still water.\r\n" );
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document.write( "The first addend in the left side is the time spent by the boat traveling upstream.\r\n" );
document.write( "The second term is the time spent traveling downstream.\r\n" );
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document.write( "To solve equation (*), multiply both sides by (u-4)*(u+4). You will get\r\n" );
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document.write( "48(u+4) + 48(u-4) = 5(u^2-16),  or\r\n" );
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document.write( "5u^2 - 96u - 80 = 0.\r\n" );
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document.write( "Solve using quadratic formula:\r\n" );
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document.write( " =  = .\r\n" );
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document.write( "Disregard the negative root.\r\n" );
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document.write( "The solution is u = 20.\r\n" );
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document.write( "Answer.  The boat speed in still water is 20 mph.\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 similar 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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