document.write( "Question 782624: how much 2% acid must be mixed with 10% acid to obtain 4000 ml of 4% acid \n" ); document.write( "

Algebra.Com's Answer #476458 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+a+\"$ = ml of 2% acid needed
\n" ); document.write( "Let $\"+b+\"$ = ml of 10% acid needed
\n" ); document.write( " $\"+.02a+\"$ = ml of acid in 2% acid
\n" ); document.write( " $\"+.1b+\"$ = ml of acid in 10% acid
\n" ); document.write( "------------------------------------
\n" ); document.write( "(1) $\"+a+%2B+b+=+4000+\"$
\n" ); document.write( "(2) $\"+%28+.02a+%2B+.1b+%29+%2F+4000+=+.04+\"$
\n" ); document.write( "---------------------------------------
\n" ); document.write( "(2) $\"+.02a+%2B+.1b+=+.04%2A4000+\"$
\n" ); document.write( "(2) $\"+.02a+%2B+.1b+=+160+\"$
\n" ); document.write( "(2) $\"+2a+%2B+10b+=+16000+\"$
\n" ); document.write( "(2) $\"+a+%2B+5b+=+8000+\"$
\n" ); document.write( "Subtract (1) from (2)
\n" ); document.write( "(2) $\"+a+%2B+5b+=+8000+\"$
\n" ); document.write( "(1) $\"+-a+-+b+=+-4000+\"$
\n" ); document.write( " $\"+4b+=+4000+\"$
\n" ); document.write( " $\"+b+=+1000+\"$
\n" ); document.write( "and, since
\n" ); document.write( "(1) $\"+a+%2B+b+=+4000+\"$
\n" ); document.write( "(1) $\"+a+=+3000+\"$
\n" ); document.write( "3000 ml of 2% acid is needed
\n" ); document.write( "1000 ml of 10% acid is needed
\n" ); document.write( "check:
\n" ); document.write( "(2) $\"+%28+.02a+%2B+.1b+%29+%2F+4000+=+.04+\"$
\n" ); document.write( "(2) $\"+%28+.02%2A3000+%2B+.1%2A1000+%29+%2F+4000+=+.04+\"$
\n" ); document.write( "(2) $\"+%28+60+%2B+100+%29+%2F+4000+=+.04+\"$
\n" ); document.write( "(2) $\"+160+=+.04%2A4000+\"$
\n" ); document.write( "(2) $\"+160+=+160+\"$
\n" ); document.write( "OK
\n" ); document.write( " \n" ); document.write( "

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