SOLUTION: A radiator contains 6 quarts of fluid, 15% of which is antifreeze. How much fluid should be drained and replaced with pure antifreeze so that the new mixture is 45% antifreeze? (Ro

Algebra ->  Customizable Word Problem Solvers  -> Mixtures -> SOLUTION: A radiator contains 6 quarts of fluid, 15% of which is antifreeze. How much fluid should be drained and replaced with pure antifreeze so that the new mixture is 45% antifreeze? (Ro      Log On

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Question 1070834: A radiator contains 6 quarts of fluid, 15% of which is antifreeze. How much fluid should be drained and replaced with pure antifreeze so that the new mixture is 45% antifreeze? (Round your answer to two decimal places.)
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = quarts of fluid to be drained
and replaced
+.15x+ = quarts of antifreeze in the fliuid
that is drained and replaced
-----------------------------------------
+%28+.15%2A%28+6+-+x+%29+%2B+x+%29+%2F+6+=+.45+
+%28+.9+-+.15x+%2B+x+%29+%2F+6+=+.45+
+%28+.85x+%2B+.9+%29+%2F+6+=+.45+
+.85x+%2B+.9+=+2.7+
+.85x+=+1.8+
+x+=+2.1176+
2.12 quarts of fluid must be drained and replaced
-------------------------
check:
+.15%2A6+=+.9+ ounces of antifreeze to start with
+.15%2A2.12+=+.318+ ounces of antifreeze is drained off
+2.12+ ounces of antifreeze is added
---------------------------------------
+.9+-+.318+%2B+2.12+=+2.702+ final ounces of antifreeze
+2.702%2F6+=+.45+
+2.702+=+2.7+
close enough
check the math
Get another opinion if needed