SOLUTION: A car radiator has a 16 quart capacity and is currently filled with a 40% antifreeze solution. How many quarts of this solution must be drained off and replaced with 100% antifree

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Question 401189: A car radiator has a 16 quart capacity and is currently filled with a 40% antifreeze solution. How many quarts of this solution must be drained off and replaced with 100% antifreeze to create a 50% antifreeze solution?
Found 2 solutions by nerdybill, josmiceli:
Answer by nerdybill(7384) (Show Source):
You can put this solution on YOUR website!
A car radiator has a 16 quart capacity and is currently filled with a 40% antifreeze solution. How many quarts of this solution must be drained off and replaced with 100% antifreeze to create a 50% antifreeze solution?
.
Let x = amount (quarts) to be drained and replaced
then
.40(16-x) + x = .50(16)
6.4-.40x + x = 8
6.4 + .60x = 8
.60x = 1.6
x = 1.6/.60
x = 2.67 quarts

Answer by josmiceli(19441) (Show Source):
You can put this solution on YOUR website!
In words:
(quarts of antifreeze started with (-) quarts of antifreeze drained off (+) quarts of antifreeze added) / ( final quarts of solution) = 50%
Let = quarts of solution drained off
Then = quarts of 100% antifreeze added
given:
= final quarts of solution
= quarts of antifreeze to start with
= quarts of antifreeze drained off
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(note: is really )

quarts
2.667 quarts of 40% solution must be removed and 2.667 quarts of
antifreeze must be added
check answer:

OK