document.write( "Question 1197751: In calm water, a motorboat can travel five times as fast as the current in the Amazon River. A trip upriver (upstream) and back totaling 96 km takes 5 hrs. Find the rate of the current. \n" ); document.write( "

Algebra.Com's Answer #831143 by ikleyn(52835) $\"\"$ $\"About$

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\n" ); document.write( "In calm water, a motorboat can travel five times as fast as the current in the Amazon River.
\n" ); document.write( "A trip upriver (upstream) and back totaling 96 km takes 5 hrs. Find the rate of the current.
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document.write( "Let x be the rate of the current in the river, in km/h.\r\n" );
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document.write( "Then the rate of the motorboat at calm water is 5x km/h;\r\n" );
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document.write( "the effective rate traveling downstream is 5x+x = 6x km/h;\r\n" );
document.write( "the effective rate traveling   upstream is 5x-x = 4x km/h.\r\n" );
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document.write( "The total round trip is 96 km; hence, one way (each way) trip is 48 km.\r\n" );
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document.write( "Time equation is\r\n" );
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document.write( "     +  = 5  hours.    (1)\r\n" );
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document.write( "Cancel common factors\r\n" );
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document.write( "     +  = 5\r\n" );
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document.write( "Simplify and find x\r\n" );
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document.write( "     = 5\r\n" );
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document.write( "     x =  = 4 km/h.\r\n" );
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document.write( "ANSWER.  The rate of the current is 4 km/h.\r\n" );
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document.write( "CHECK.  We will check equation (1):   +  =  +  = 3 + 2 = 5 hours.   ! correct !\r\n" );
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