document.write( "Question 449124: The radiator in Natalie�s car contains 6.3 L of antifreeze and water. This mixture is 30% antifreeze. How much of this mixture should she drain and replace with pure antifreeze so that there will be a mixture of 50% antifreeze? \n" ); document.write( "

Algebra.Com's Answer #853356 by ikleyn(53615) $\"\"$ $\"About$

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\n" ); document.write( "The radiator in Natalie's car contains 6.3 L of antifreeze and water. This mixture is 30% antifreeze.
\n" ); document.write( "How much of this mixture should she drain and replace with pure antifreeze so that there will be a mixture of 50% antifreeze?
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\n" ); document.write( "\n" ); document.write( " In the post by @mananth, the solution is incorrect, because his starting equation is written incorrectly.\r
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document.write( "Let x be the volume of the original mixture to drain and replace with pure antifreeze.\r\n" );
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document.write( "Then the balance equation for pure antifreeze content is\r\n" );
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document.write( "    0.3*(6.3-x) + x = 0.5*6.3.\r\n" );
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document.write( "Simplify and find x\r\n" );
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document.write( "    0.3*6.3 - 0.3x + x = 0.5*6.3,\r\n" );
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document.write( "    -0.3x + x = 0.5*6.3 - 0.3*6.3,\r\n" );
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document.write( "         0.7x =  (0.5*-0.3)*6.3\r\n" );
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document.write( "         0.7x =     0.2*6.3\r\n" );
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document.write( "            x =     0.2*9 = 1.8.\r\n" );
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document.write( "ANSWER.  1.8 liters of the original mixture should be drained and replaced by the pure antifreeze.\r\n" );
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\n" ); document.write( "\n" ); document.write( "Solved correctly.\r
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