Question 53029This question is from textbook
: A health clinic uses a solution of bleach to sterilize petri dishes in which cultures are grown. The sterilization tank holds 100 gal. of a solution of 2% ordinary household bleach mixed with pure distilled water.. New research indicates that the concentration of bleach should be 5% for complete sterilization. How much of the solution should be drained and replaced with bleach to increase the bleach content to the recommended level?
This question is from textbook
Answer by ptaylor(2198)   (Show Source):
You can put this solution on YOUR website! Let x=amt of the initial mixture (100 gal of 2% bleach (and 98% distilled water)) that should be drained and replaced with 100% bleach so that the final mixture (100 gal) is 5% bleach (and 95% distilled water).
First, I will solve this problem by focusing on the distilled water and then I will solve it again focusing upon the bleach:
Amt of distilled water in initial mixture (100)(.98) minus amt of distilled water that was drained out (.98x) equals amt of distilled water in final mixture (100)(.95). The equation to solve is:
(100)(.98)-.98x=(100)(.95) simplifying, we get
98-.98x=95
-.98x=-3
x=3.06 gal
Now, we'll focus on the bleach:
Amt of bleach in the initial mixture (100)(.02) minus amt of bleach that was drained out (.02x) plus the amt of bleach that was added (x)(1)equals amt of bleach in final mixture (100)(.05). The equation to solve is:
(100)(.02)-.02x+x=(100)(.05) simplifying, we get
2+.98x=5
.98x=3
x=3.06 gal
Hope this helps -----ptaylor
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