document.write( "Question 515871: A laboratory technician prepares 200 mL of 35% ethyl alcohol from a 95% ethyl alcohol stock solution.\r
\n" ); document.write( "\n" ); document.write( "Determine, to the nearest mL, the amount of 95% ethyl alcohol that is needed.\r
\n" ); document.write( "\n" ); document.write( "Determine, to the nearest mL, the amount of distilled water that is added. \n" ); document.write( "

Algebra.Com's Answer #344187 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+a+\"$ = ml of 95% alcohol needed
\n" ); document.write( "Let $\"+b+\"$ = ml of water needed
\n" ); document.write( "given:
\n" ); document.write( "(1) $\"+a+%2B+b+=200+\"$ ml
\n" ); document.write( "(2) $\"+.95a+%2F+%28+a+%2B+b+%29+=+.35+\"$
\n" ); document.write( "----------------------
\n" ); document.write( "(2) $\"+.95a++=+.35%2A%28a+%2B+b%29+\"$
\n" ); document.write( "(2) $\"+.95a+=+.35a+%2B+.35b+\"$
\n" ); document.write( "(2) $\"+.6a+=+.35b+\"$
\n" ); document.write( "(2) $\"+60a+=+35b+\"$
\n" ); document.write( "(2) $\"+12a+=+7b+\"$
\n" ); document.write( "and,
\n" ); document.write( "(1) $\"+a+=+200+-+b+\"$
\n" ); document.write( "By substitution:
\n" ); document.write( "(2) $\"+12%2A%28+200+-+b+%29+=+7b+\"$
\n" ); document.write( "(2) $\"+2400+-+12b+=+7b+\"$
\n" ); document.write( "(2) $\"+19b+=+2400+\"$
\n" ); document.write( "(2) $\"+b+=+126.32+\"$
\n" ); document.write( "and
\n" ); document.write( "(1) $\"+a+=+200+-+b+\"$
\n" ); document.write( "(1) $\"+a+=+200+-+126.32+\"$
\n" ); document.write( "(1) $\"+a+=+73.68+\"$
\n" ); document.write( "74 ml of 95% alcohol are needed
\n" ); document.write( "126 ml of water are needed
\n" ); document.write( "check answer:
\n" ); document.write( "(2) $\"+.95a+%2F+%28+a+%2B+b+%29+=+.35+\"$
\n" ); document.write( "(2) $\"+.95%2A74+%2F+200+=+.35+\"$
\n" ); document.write( "(2) $\"+70.3+%2F+200+=+.35+\"$
\n" ); document.write( "(2) $\"+70.3+=+70+\"$
\n" ); document.write( "close enough \n" ); document.write( "

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