document.write( "Question 275411: In a chemistry class, 6 liters of 4% silver iodide solution must be mixed with 10% solution to get a 6% solution. How many liters of 10% solution are needed? \n" ); document.write( "

Algebra.Com's Answer #854108 by greenestamps(13320) $\"\"$ $\"About$

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\n" ); document.write( "The responses you have received so far all use the standard formal algebraic method for solving the problem -- writing and solving an equation which says the sum of the amounts of silver iodide in the two ingredients is equal to the amount in the mixture.

\n" ); document.write( "If a formal algebraic solution is needed, then that is the standard method and almost certainly the fastest formal method.

\n" ); document.write( "But 2-part mixture problems like this can be solved much faster using an informal method using the ratio of the amounts of the two ingredients.

\n" ); document.write( "Here in words is the solution to this problem using this method.

\n" ); document.write( "(1) The target 6% solution is \"twice as close to 4% as it is to 10%\" (the difference between 4% and 6% is 2%; the difference between 6% and 10% is 4%.)
\n" ); document.write( "(2) That means the amount of 4% silver iodide in the mixture must be twice as much as the amount of 10% silver iodide.
\n" ); document.write( "(3) The mixture uses 6 liters of the 4% silver iodide, so it must use 3 liters of the 10% silver iodide.

\n" ); document.write( "ANSWER: 3 liters

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