<PRE><B>Question 181015</B>
a health clinic uses a solution of bleach to sterilize petri dishes in which cultures are grown.
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The sterilization tank contains 100 gal of a solution of 2% ordinary household bleach mixed with pure distilled water. 
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New research indicates that the concentration of bleach should be 5% for complete sterilization. 
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How much of the solution should be drained and replaced with bleach to increase the bleach content to the recommended level?
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Equation:
bleach -bleach + bleach = bleach
0.02*100 -0.02x + x = 0.05(100)

Multiply thru by 100 to get:
2*100 - 2x + 100x = 5*100
98x = 300
x = 3.06 gallons
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Cheers,
Stan H.
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