document.write( "Question 1098348: You need 1190 mL of a 70% alcohol solution. On hand, you have a 85% alcohol mixture. How much of the 85% alcohol mixture and pure water will you need to obtain the desired solution?
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Algebra.Com's Answer #716139 by ikleyn(52782) $\"\"$ $\"About$

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document.write( "Let x be the volume of the 85% alcohol mixture to obtain the desired 1190 mL of the 70% solution.\r\n" );
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document.write( "Then the volume of water is (1190-x) mL, to provide the total volume of the final mixture of 1190 mL.\r\n" );
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document.write( " \"x\" mL of the 85% alcohol mixture contains 0.85*x mL of the pure alcohol.\r\n" );
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document.write( "Exactly this amount of the pure alcohol goes to the final solution.\r\n" );
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document.write( "Thus the final solution contains  0.85*x mL of the pure alcohol and has the volume of 1190 mL.\r\n" );
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document.write( "The fraction   is the ratio of the pure alcohol volume to the total liquid volume, i.e concentration.\r\n" );
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document.write( "According to the condition, the concentration of the final mixture must be 70%, i.e. 0.7.  It gives you an equation\r\n" );
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document.write( " = 0.7.\r\n" );
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document.write( "From the equation,  x =  = 980.\r\n" );
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document.write( "Answer.  980 mL of the 85% solution should be mixed with 1190-980 = 210 mL of water to get 1190 mL of the 70% solution.\r\n" );
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document.write( "Check.    = 0.7,  or 70%.   ! Correct !\r\n" );
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