document.write( "Question 519782: how many ounces of water must be evaporated from 50oz of a 12% salt solution to produce a 15% salt solution? I know that the answer is 10oz, however i do not know how the book got that as the answer. my teacher is using a 3 by 3 box set up to answer these word problems. I just cant figure this one out... \n" ); document.write( "

Algebra.Com's Answer #345777 by oberobic(2304) $\"\"$ $\"About$

You can put this solution on YOUR website!
This is an interesting variation on a typical solution problem. The same rule of keeping track of how much 'pure' stuff still applies, but in this case we are evaporating water to increase the salt concentration.
\n" ); document.write( ".
\n" ); document.write( "You have 50 oz of 12% salt solution. That means have .12*50 = 6.0 oz of pure salt.
\n" ); document.write( ".
\n" ); document.write( "You need to produce 15% salt solution.
\n" ); document.write( "So 6 oz of pure salt = 15% of how much?
\n" ); document.write( ".
\n" ); document.write( ".15x = 6
\n" ); document.write( "x = 6/.15
\n" ); document.write( "x = 40
\n" ); document.write( ".
\n" ); document.write( "That means that if you have 40 oz of solution containing 6 oz of pure salt, you have a 15% solution.
\n" ); document.write( "You can check this by dividing 6/40 = .15
\n" ); document.write( ".15 * 100 = 15%
\n" ); document.write( "Correct.
\n" ); document.write( ".
\n" ); document.write( "You have 50 oz of solution now, and you need 40 oz of solution, so you need to evaporate 10 oz of water.
\n" ); document.write( ".
\n" ); document.write( "Done. \n" ); document.write( "

\n" );