SOLUTION: A tank contains 20 gallons of antifreeze solution. When it is full, it contains 15% antifreeze. How many gallons must be replaced by an 80% antifreeze solution to get 20 gallons
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Question 529835: A tank contains 20 gallons of antifreeze solution. When it is full, it contains 15% antifreeze. How many gallons must be replaced by an 80% antifreeze solution to get 20 gallons of a 70% solution? Answer by josmiceli(19441) (Show Source):
You can put this solution on YOUR website! Let = gallons of 15% antifreeze to be
removed and replaced with 80% antifreeze
In words:
( gallons of pure antifreeze at end)/( gallons of solution at end) = 70%
------------- gallons of pure antifreeze at start gallons of solution left after removal of gallons = pure antifreeze left after removal of gallons = pure antifreeze in 80% solution added
The total gallons of solution has not changed
16.923 gallons must be removed and replace with
16.923 gallons of 80% antifreeze
-----------
check: gallons of solution left after removal of gallons = pure antifreeze left after removal of gallons = pure antifreeze in 80% solution added
error due to rounding off- OK
