SOLUTION: A tank at a marine exhibit contains 2000 gallons of seawater. The seawater is 7.5% salt. How many gallons to the nearest gallon of fresh water must be added to the tank so that the

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Question 892841: A tank at a marine exhibit contains 2000 gallons of seawater. The seawater is 7.5% salt. How many gallons to the nearest gallon of fresh water must be added to the tank so that the mixture only contains 7%?
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39617)   (Show Source): You can put this solution on YOUR website!
The problem description is both wrong and incomplete. Where did the question come from?
Seawater has about 3.5% "salinity", largely of sodium chloride. What density is given for your "7.5%" salt seawater? For the world's seawater at 3.5% salinity, it is 1.025 grams/ml.
Answer by MathTherapy(10552)   (Show Source): You can put this solution on YOUR website!

A tank at a marine exhibit contains 2000 gallons of seawater. The seawater is 7.5% salt. How many gallons to the nearest gallon of fresh water must be added to the tank so that the mixture only contains 7%?


Let amount of water to be added be W

Then: .925(2000) + W = .93(2000 + W)

1850 + W = 1860 + .93W

W - .93W = 1860 - 1850

.07W = 10

Amount of water to add = , or 142.8571429 ≈  gallons 

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