SOLUTION: A tank with a radius of 6 feet contains 1 foot of 5% acid solution. In order to mix an 8% solution, a 20% solution is added. How much 20% solution will be added? (Find ft3, gallons

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Question 849548: A tank with a radius of 6 feet contains 1 foot of 5% acid solution. In order to mix an 8% solution, a 20% solution is added. How much 20% solution will be added? (Find ft3, gallons, and level change in tank). Please Help me find an easy way to understand how to do these...
Answer by josgarithmetic(39659) About Me  (Show Source):
You can put this solution on YOUR website!
1 cubic foot = %28576%2F77%29 U.S. Gallons;------------ http://en.wikipedia.org/wiki/Cubic_feet

Volume of 5% acid in the tank:

Want to add some v gallons of 20% acid to that to make 8% acid result.
%28846%2A5%2B20%2Av%29%2F%28v%2B846%29=8
20v%2B846%2A5=8%28v%2B846%29
20v%2B846%2A5=8v%2B8%2A846
%2820-8%29v=%288-5%29846
12v=3%2A846
v=3%2A846%2F12
highlight%28v=211.5%29 gallons of the 20% acid.

You can convert that volume into cubic feet, and use highlight_green%28y%2Api%2A6%5E2=211.5%2877%2F576%29%29 and solve for y, here being the vertical increment of change for the 211.5 gallon addition of the added acid.