document.write( "Question 1156383: Misty wishes to obtain 85 ounces of a 40% acid solution by combining a 72% acid solution with a 25% acid solution. How much of each solution should misty use? \n" ); document.write( "
Algebra.Com's Answer #779079 by greenestamps(13203)\"\" \"About 
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\n" ); document.write( "You should understand how to solve a two-part mixture problem like this using formal algebra. But if a formal algebraic solution is not required, there is a MUCH faster way to solve the problem.

\n" ); document.write( "A typical algebraic solution would look something like this....

\n" ); document.write( "x = ounces of 72% acid
\n" ); document.write( "85-x = ounces of 25% acid

\n" ); document.write( "The combined acid in the two ingredients is equal to the acid in 40% of the total 85 ounces:

\n" ); document.write( "\".72%28x%29%2B.25%2885-x%29+=+.40%2885%29\"
\n" ); document.write( "\".72x%2B21.25-.25x+=+34\"
\n" ); document.write( "\".47x+=+12.75\"
\n" ); document.write( "\"x+=+12.75%2F.47+=+1275%2F47\"

\n" ); document.write( "The amount of 72% acid is 1275/47 ounces; the amount of 25% acid is 85-(1275/47) = 2720/47 ounces. Those are ugly fractions; and we had to do a lot of ugly calculations to find them.

\n" ); document.write( "Convert those numbers to decimals or percents if required....

\n" ); document.write( "Here is a much faster path to the same ugly answers.

\n" ); document.write( "On a number line, 40% is 15/47 of the way from 25% to 72%.
\n" ); document.write( "That means 15/47 of the mixture needs to be the 72% acid.
\n" ); document.write( "15/47 of the total 85 ounces is 1275/47 ounces.

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