SOLUTION: A radiator contains 10 quarts of fluid, 30% of which is antifreeze. How much fluid should be drained and replaced with pure antifreeze so that the new mixture is 40% antifreeze?

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Question 763949: A radiator contains 10 quarts of fluid, 30% of which is antifreeze. How much fluid should be drained and replaced with pure antifreeze so that the new mixture is 40% antifreeze?
Found 2 solutions by stanbon, josmiceli:
Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website!
A radiator contains 10 quarts of fluid, 30% of which is antifreeze. How much fluid should be drained and replaced with pure antifreeze so that the new mixture is 40% antifreeze?
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Equation:
active - active + active = active
0.30*10 - 0.30x + 1.00x = 0.40*10
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30*10 - 30x + 100x = 40*10
70x = 10*10
x = 10/7 = 1.4286 quarts (amt. to remove and replace)
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Cheers,
Stan H.
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Answer by josmiceli(19441) (Show Source):
You can put this solution on YOUR website!
Let = quarts of fluid to be drained and replaced
with pure antifreeze
= quarts of pure antifreeze in fluid drained off
quarts of pure antifreeze originally in fluid
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( note that you start with quarts and end with quarts )

1.4286 quarts of fluid must be drained off and
replaced with pure antifreeze
check:

OK