SOLUTION: A health clinic uses a solution of bleach to sterilize petri dishes in which cultures are grown. The sterilization tank contains 90 gal of a solution of 4% ordinary household bleac

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Question 712569: A health clinic uses a solution of bleach to sterilize petri dishes in which cultures are grown. The sterilization tank contains 90 gal of a solution of 4% ordinary household bleach mixed with pure distilled water. New research indicates that the concentration of bleach should be 8% for complete sterilization. How much of the solution should be drained and replaced with bleach to increase the bleach content to the recommended level?
Answer by stanbon(75887) About Me  (Show Source):
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A health clinic uses a solution of bleach to sterilize petri dishes in which cultures are grown. The sterilization tank contains 90 gal of a solution of 4% ordinary household bleach mixed with pure distilled water. New research indicates that the concentration of bleach should be 8% for complete sterilization. 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
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0.04*90 - 0.04x + 1*x = 0.08*90
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Multiply thru by 100 to get:
4*90 - 4x + 100x = 8*90
96x = 4*90
x = (4*90)/96
x = 3.9167 gallons (amt. that should be removed and replaced)
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Cheers,
Stan H.