document.write( "Question 1165827: A flask contains 500 ml of an 80% alcohol solution in water. How much of this solution must be drawn off and replaced by water to obtain a solution having a concentration of 25% alcohol? \n" ); document.write( "

Algebra.Com's Answer #790299 by ikleyn(52786) $\"\"$ $\"About$

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\n" ); document.write( "A flask contains 500 ml of an 80% alcohol solution in water. How much of this solution must be drawn off and replaced by water
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document.write( "Let V be the volume to drain off from 500 mL of the original mixture.\r\n" );
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document.write( "Step 1:  Draining.  After draining,  you have 500-V mL of the 80% mixture.\r\n" );
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document.write( "Step 2:  Replacing.  Then you add V mL of water (the replacing step).\r\n" );
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document.write( "                     After the replacing,  you have the same total liquid volume of 500 mL.\r\n" );
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document.write( "It contains  0.8*(500-V)  of the pure alcohol.\r\n" );
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document.write( "So, your \"concentration equation\" is\r\n" );
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document.write( "     = 0.25.    (1)\r\n" );
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document.write( "The setup is done and completed.\r\n" );
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document.write( "Now you need to solve your basic equation  (1).  Multiply both sides by 500.\r\n" );
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document.write( "    0.8*(500-V) = 0.25*500\r\n" );
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document.write( "    0.8*500 - 0.8V = 125\r\n" );
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document.write( "    400     - 125  = 0.8V\r\n" );
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document.write( "    V =  = 343.75 mL.\r\n" );
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document.write( "Answer.  343.75 mL of the original mixture should be drained and replaced with water.\r\n" );
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\n" ); document.write( "\n" ); document.write( "It is a standard and typical mixture problem.\r
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\n" ); document.write( "\n" ); document.write( "In this site, there is a bunch of lessons, covering various types of mixture problems. See introductory lessons\r
\n" ); document.write( "\n" ); document.write( "    - Mixture problems\r
\n" ); document.write( "\n" ); document.write( "    - More Mixture problems\r
\n" ); document.write( "\n" ); document.write( "    - Solving typical word problems on mixtures for solutions \r
\n" ); document.write( "\n" ); document.write( "    - Word problems on mixtures for antifreeze solutions (*)\r
\n" ); document.write( "\n" ); document.write( "    - Word problems on mixtures for alloys \r
\n" ); document.write( "\n" ); document.write( "    - Typical word problems on mixtures from the archive\r
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\n" ); document.write( "\n" ); document.write( "Of these lessons, the closest solutions to your problem you will find in the lesson marked (*) in the list.\r
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\n" ); document.write( "\n" ); document.write( "Read the lessons and become an expert in solution the mixture word problems.\r
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\n" ); document.write( "\n" ); document.write( "Also, you have this free of charge online textbook in ALGEBRA-I in this site\r
\n" ); document.write( "\n" ); document.write( "    - ALGEBRA-I - YOUR ONLINE TEXTBOOK.\r
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\n" ); document.write( "\n" ); document.write( "The referred lessons are the part of this online textbook under the topic \"Mixture problems\".\r
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\n" ); document.write( "\n" ); document.write( "Save the link to this online textbook together with its description\r
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\n" ); document.write( "\n" ); document.write( "Free of charge online textbook in ALGEBRA-I
\n" ); document.write( "https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson\r
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\n" ); document.write( "\n" ); document.write( "to your archive and use it when it is needed.\r
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