SOLUTION: There are 20 kilograms of a solution that is 10% salt. How many kilograms of salt must be added to make a solution that is 25% salt?

Question 147693: There are 20 kilograms of a solution that is 10% salt. How many kilograms of salt must be added to make a solution that is 25% salt?
Found 2 solutions by stanbon, Nate:
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
There are 20 kilograms of a solution that is 10% salt. How many kilograms of salt must be added to make a solution that is 25% salt?
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EQUATION:
salt + salt = salt
Let x be the amount of pure salt that must be added.
0.10(20) + x = 0.25(20+x)
2 + x = 5 + (1/4)x
(3/4)x = 3
x = 4 kg (amt. of pure salt that must be added.
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Cheers,
Stan H.
Answer by Nate(3500) (Show Source): You can put this solution on YOUR website!
( 20 * 10% + x * 100% ) / ( 20 + x ) = 25%
( 20 * 0.1 + x ) / ( 20 + x ) = 0.25
( 2 + x ) / ( 20 + x ) = 0.25
2 + x = 0.25( 20 + x )
2 + x = 5 + 0.25x
0.75x = 3
x = 4kg salt
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