document.write( "Question 1208942: The speed of a moving walkway is typically about 2.5 feet per second. Walking on such a moving walkway, it takes Judy a total of 40 seconds to travel 50 feet with the movement of the walkway and then back against the movement of the walkway. What is Judy's normal walking speed? \r
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Algebra.Com's Answer #847477 by ikleyn(52781) $\"\"$ $\"About$

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\n" ); document.write( "The speed of a moving walkway is typically about 2.5 feet per second.
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document.write( "Let x be the Judy' normal speed, in ft/s.\r\n" );
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document.write( "Then Judy' speed with the walkway is x+2.5 ft/s,\r\n" );
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document.write( "and against the walkway it is x-2.5 ft/s.\r\n" );
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document.write( "Write and use the time equation\r\n" );
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document.write( "     +  = 40  seconds    (1)\r\n" );
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document.write( "for the total trip.\r\n" );
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document.write( "To solve, multiply both sides by (x-2.5)*(x+2.5) = x^2 - 6.25.  You will get\r\n" );
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document.write( "    50(x-2.5) + 50*(x+2.5) =  40(x^2 -6.25),\r\n" );
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document.write( "    100x = 40x^2 - 250,\r\n" );
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document.write( "    40x^2 - 100x - 250 = 0,\r\n" );
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document.write( "    4x^2 - 10x - 25 = 0,\r\n" );
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document.write( "    x =  =  = .\r\n" );
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document.write( "We want the positive root and deny the negative one\r\n" );
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document.write( "    x =  = 4.045085 ft/s  (rounded).\r\n" );
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document.write( "CHECK  equation  (1):    = 40.0 seconds, \r\n" );
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document.write( "                        which convinces me that the solution is good.\r\n" );
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document.write( "ANSWER.  The Judy' walking speed is about 4.05 ft/s.\r\n" );
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