document.write( "Question 1121497: A coal contains 2.4% of water. After drying, the moisture-free residue contains 71.0% carbon. Determine the percentage of carbon on \"wet basis\". All percentage are by weight. \n" ); document.write( "

Algebra.Com's Answer #737404 by ikleyn(52786) $\"\"$ $\"About$

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document.write( "Let M be the mass of the coal before drying.\r\n" );
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document.write( "Since it contains 2.4% of water, after drying the mass will be  M - 0.024*M.\r\n" );
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document.write( "Let C be the mass of carbon in this coal.\r\n" );
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document.write( "Then the condition says  \r\n" );
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document.write( "     = 0.71.\r\n" );
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document.write( "Therefore,\r\n" );
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document.write( "    C = 0.71*(M-0.024*M) = 0.71*M*(1-0.024),   or\r\n" );
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document.write( "     = 0.71*(1-0.024) = 0.693 (approximately),   or  69.3%.\r\n" );
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document.write( "Answer.  Before drying, the percentage of carbon in the coal is  69.3%, approximately (rounded to one decimal place).\r\n" );
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