document.write( "Question 1202398: A boat traveled 280 miles downstream and back. The trip downstream took 14 hours. The trip back took 140 hours. Find the speed of the boat in still water and the speed of the current. \n" ); document.write( "

Algebra.Com's Answer #837192 by math_helper(2461) $\"\"$ $\"About$

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document.write( "Downstream:  V = v + c  
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document.write( "    where 
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document.write( "        V = total speed, 
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document.write( "        v = speed of boat in still water, and
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document.write( "        c = speed of current\r
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document.write( "  V = 280mi/14hr = 20mi/hr   \r
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document.write( "This tells us
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document.write( "   v + c = 20      (1)\r
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document.write( "For the upstream direction, we subtract the speed of the current:
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document.write( "   v - c = 280/140
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document.write( "   v - c = 2       (2)\r
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document.write( "Add (1) and (2):  2v = 22 -->  v = 11  -->  c = 9 (plug v=11 into (1) or (2))\r
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document.write( "Ans:
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document.write( "  Speed of boat in still water is   11mi/hr
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document.write( "  Speed of current is                9mi/hr\r
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document.write( "This solution does make the assumption that the speed of the boat and the speed of the current add / subtract in a straightforward (linear) manner.
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