A health clinic uses a solution of bleach to sterilize petri dishes in which cultures are grown. the sterilization tank contains 120 gal of a solution of 4% ordinary household bleach mixed with pure distilled water. new research indicates that the concentration of bleach should be 7% for complete sterilization. how much of the solution should be drained and replaced with bleach to increase the bleach content to the recommended level?

Question

Aubrey Carrillo

Mathematics

25 October, 05:52

A health clinic uses a solution of bleach to sterilize petri dishes in which cultures are grown. the sterilization tank contains 120 gal of a solution of 4% ordinary household bleach mixed with pure distilled water. new research indicates that the concentration of bleach should be 7% 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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Jessica Espinoza · Answer 1

Let g represent the number of gallons to be drained. Then the amount (in gallons) of bleach in the tank will be given by

... 4% * (120 - g) + 100%*g = 7%*120

... 4.8 -.04g + g = 8.4

... 0.96g = 3.6

... g = 3.6/0.96 = 3.75

3 3/4 gallons need to be drained and replaced with 3 3/4 gallons of bleach.