document.write( "Question 28406: A chmistry student needs 10L of a 12% acid solution. The laboratory has an ample amounts of 10% and 20% acid solutions. How many liters of each solution should the student mix? \n" ); document.write( "
Algebra.Com's Answer #15450 by longjonsilver(2297)\"\" \"About 
You can put this solution on YOUR website!
mixture questions are all about BEFORE and AFTER...they have to be equal.\r
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\n" ); document.write( "\n" ); document.write( "Let x=amount of 10% acid to be added.
\n" ); document.write( "and so how much of the 20% acid? Leap of faith... it is everything else of the 10litres of the final amount surely? so (10-x)litres of the 20% acid.\r
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\n" ); document.write( "\n" ); document.write( "--> 0.10*x + 0.20(10-x) is everything before mixing.\r
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\n" ); document.write( "\n" ); document.write( "After mixing, we have 10 litres of a 12% acid --> 0.12*10\r
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\n" ); document.write( "\n" ); document.write( "so 0.10*x + 0.20(10-x) = 0.12*10
\n" ); document.write( "0.1x + 2 - 0.2x = 1.2
\n" ); document.write( "-0.1x + 2 = 1.2
\n" ); document.write( "-0.1x = -0.8
\n" ); document.write( "x = -0.8/-0.1
\n" ); document.write( "x = 8 litres\r
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\n" ); document.write( "\n" ); document.write( "and so we need 8 litres of the 10% acid and 2 litres of the 20% acid.\r
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\n" ); document.write( "\n" ); document.write( "Easy? :-)\r
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\n" ); document.write( "\n" ); document.write( "jon.
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