SOLUTION: The radiator of a car is filled with 3.8L of a solution of 45% antifreeze. How much of the solution should be drained and replaced with antifreeze to increase the concentration of

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Question 694592: The radiator of a car is filled with 3.8L of a solution of 45% antifreeze. How much of the solution should be drained and replaced with antifreeze to increase the concentration of antifreeze to 60%? Round to the nearest tenth of liter.
I tried the problem and got it wrong. I did:
3.8L/1=45%/60% = 2.9L

Found 2 solutions by ankor@dixie-net.com, josmiceli:
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
The radiator of a car is filled with 3.8L of a solution of 45% antifreeze.
How much of the solution should be drained and replaced with antifreeze to increase the concentration of antifreeze to 60%?
Round to the nearest tenth of liter.
:
Use this equation:
:
Let x = amt to be removed and then added
.45(3.8-x) + 1x = .60(3.8)

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
You start with 3.8 liters and end with 3.8 liters
This is one of the keys.
+.45%2A3.8+=+1.71+ liters of pure antifreeze to start with
Let +x+ = liters to be drained off and replaced
with pure antifreeze
+.45x+ = liters of pure antifreeze drained off.
-----------------------------------------
+%28+1.71+-+.45x+%2B+x+%29+%2F+3.8+=+.6+
+1.71+%2B+.55x+=+.6%2A3.8+
+1.71+%2B+.55x+=+2.28+
+.55x+=+2.28+-+1.71+
+.55x+=+.57+
+x+=+1.0364+
1.036 liters of the solution should be drained and
replaced with pure antifreeze
-----------------
check:
+%28+1.71+-+.45x+%2B+x+%29+%2F+3.8+=+.6+
+%28+1.71+-+.45%2A1.0364+%2B+1.0364+%29+%2F+3.8+=+.6+
+1.71+-+.4662+%2B+1.036+=+.6%2A3.8+
+1.71+%2B+.5700+=+2.28+
+2.28+=+2.28+
Did I get it right?