document.write( "Question 288054:  A----------60m-------------C------40m-------B\r
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document.write( "Alphonse starts at point A and runs at a constant rate towards point C. At the same time, Brigitte starts at point B and runs towards point C also at
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document.write( "a constant rate. They arrive at C at exactly the same moment. If they continue running in the same directions, Alphonse arrives at B exactly 10 seconds before Brigitte arrives at A. How fast was Brigitte running?\r
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document.write( "(A) 3 m/s (B) 10/3 m/s (C) 13/3 m/s (D) 5 m/s (E) Not enough information \n" );
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| Algebra.Com's Answer #208778 by stanbon(75887)      You can put this solution on YOUR website! A----------60m-------------C------40m-------B \r \n" ); document.write( "\n" ); document.write( "Alphonse starts at point A and runs at a constant rate towards point C. At the same time, Brigitte starts at point B and runs towards point C also at \n" ); document.write( "a constant rate. They arrive at C at exactly the same moment. \n" ); document.write( "--- \n" ); document.write( "1st leg: \n" ); document.write( "Alphonse DATA: \n" ); document.write( "distance = 60m ; rate = a m/sec ; time = 60/a seconds \n" ); document.write( "Brigitte DATA: \n" ); document.write( "distance = 40m ; rate = b m/sec ; time = 40/b seconds \n" ); document.write( "--- \n" ); document.write( "1st leg Equation: \n" ); document.write( "60/a = 40/b \n" ); document.write( "a = (3/2)b \n" ); document.write( "------------ \n" ); document.write( "If they continue running in the same directions, Alphonse arrives at B exactly 10 seconds before Brigitte arrives at A. How fast was Brigitte running? \n" ); document.write( "--------------- \n" ); document.write( "Total trip: \n" ); document.write( "Alphonse DATA: \n" ); document.write( "distance = 100m ; rate = a m/sec ; time = 100/a m/sec \n" ); document.write( "Brigitte DATA: \n" ); document.write( "distance = 100m ; rate = b m/sec ; time = 100/b m/sec \n" ); document.write( "Total trip Equation: \n" ); document.write( "Brit time - Alphon time = 10 sec. \n" ); document.write( "100/b - 100/a = 10 sec \n" ); document.write( "Multiply thru by ab to get: \n" ); document.write( "100a - 100b = 10ab \n" ); document.write( "--- \n" ); document.write( "Substitute for \"a\" and solve for \"b\": \n" ); document.write( "100(3/2)b - 100b = 10(3/2)b^2 \n" ); document.write( "(1/2)100b = 15b^2 \n" ); document.write( "15b^2 - 50b = 0 \n" ); document.write( "b(15b-50) = 0 \n" ); document.write( "b = 0 or b = 50/15 = 10/3 \n" ); document.write( "--- \n" ); document.write( "Brigitte rate = 10/3 meters/sec \n" ); document.write( "=================================== \n" ); document.write( "Cheers, \n" ); document.write( "Stan H.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( "(A) 3 m/s (B) 10/3 m/s (C) 13/3 m/s (D) 5 m/s (E) Not enough information \n" ); document.write( " \n" ); document.write( " |