document.write( "Question 1203109: It took a patrol boat 5 hours to travel 60 km up a river against the current, and 3 hours for the return trip with the current. Find the speed of the boat in still water and the speed of the current. \n" ); document.write( "

Algebra.Com's Answer #838404 by ikleyn(52788) $\"\"$ $\"About$

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\n" ); document.write( "It took a patrol boat 5 hours to travel 60 km up a river against the current,
\n" ); document.write( "and 3 hours for the return trip with the current.
\n" ); document.write( "Find the speed of the boat in still water and the speed of the current.
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document.write( "Let u be the rate of the boat in still water \r\n" );
document.write( "and v be the rate of the current.\r\n" );
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document.write( "Then you have these two equations:\r\n" );
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document.write( "    for the effective upstream   rate  u - v = 60/5 = 12 kilometers per hour;    (1)\r\n" );
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document.write( "    for the effective downstream rate  u + v = 60/3 = 20 kilometers per hour.    (2)\r\n" );
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document.write( "Adding equations (1) and (2), you get\r\n" );
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document.write( "    2u = 12 + 20 = 32 km/h;  hence,  u = 32/2 = 16 km/h.\r\n" );
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document.write( "Subtracting equation (1) from equation (2), you get\r\n" );
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document.write( "    2v = 20 - 12 = 8 km/h;   hence,  v = 8/2 = 4 km/h.\r\n" );
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document.write( "ANSWER.  The rate of the boat in still water is 16 km/h.  The rate of the current is 4 km/h.\r\n" );
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\n" ); document.write( "\n" ); document.write( "To see other similar solved problems, look into 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
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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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