document.write( "Question 272631: How many quarts of pure antifreeze must be added to 6 quarts of a 10% solution to obtain a 20% antifreeze soltuion? (Round to the nearest tenth.) \n" ); document.write( "

Algebra.Com's Answer #854093 by ikleyn(53742) $\"\"$ $\"About$

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\n" ); document.write( "How many quarts of pure antifreeze must be added to 6 quarts of a 10% solution to obtain a 20% antifreeze soltuion?
\n" ); document.write( "(Round to the nearest tenth.)
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\n" ); document.write( "\n" ); document.write( "        The solution in the post by @mananth is INCORRECT: its governing equation\r
\n" ); document.write( "\n" ); document.write( "        is written incorrectly.\r
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\n" ); document.write( "\n" ); document.write( "        I came to provide a correct solution.\r
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document.write( "Let x be the volume of pure antifreeze to add, in quarts.\r\n" );
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document.write( "Then the governing equation is \r\n" );
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document.write( "    x + 0.1*6 = 0.2(x+6)    <<<---===  the amount of the pure antifreeze in ingredients (left side)\r\n" );
document.write( "                                       and in the mixture (right side)\r\n" );
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document.write( "Simplify and find x\r\n" );
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document.write( "    x + 0.6 = 0.2x + 1.2,\r\n" );
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document.write( "    x - 0.2x = 1.2 - 0.6,\r\n" );
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document.write( "      0.8x   =    0.6,\r\n" );
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document.write( "         x   =    0.6/0.8 = 6/8 = 3/4 = 0.75.\r\n" );
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document.write( "ANSWER.  0.75 quarts of pure antifreeze should be added.\r\n" );
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\n" ); document.write( "\n" ); document.write( "Solved correctly.\r
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\n" ); document.write( "\n" ); document.write( "Notice that the instruction for rounding is not appropriate to the problem.\r
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\n" ); document.write( "\n" ); document.write( "It tells me that the problem's composer was not focused on the problem when created it.
\n" ); document.write( "Or simply does not understand what he/she composes.\r
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