SOLUTION: How much pure water must be added to 4.5 litres of 87% acid solution to dilute it to 64% solution ?

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Question 1033433: How much pure water must be added to 4.5 litres of 87% acid solution to dilute it to 64% solution ?
Found 3 solutions by Alan3354, josmiceli, jorel555:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
How much pure water must be added to 4.5 litres of 87% acid solution to dilute it to 64% solution ?
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Add L liters of water.
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4.5*0.87 + L*0 = (4.5 + L)*0.64
Solve for L

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = liters of pure water to be added
+.87%2A4.5+=+3.915+ liters of pure acid in 87% solution
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++3.915+%2F+%28+x+%2B+4.5+%29+=+.64+
+3.915+=+.64%2A%28+x+%2B+4.5+%29+
+3.915+=+.64x+%2B+2.88+
+.64x+=+1.035+
+x+=+1.6172+
1.6172 liters of pure water should be added
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check:
++3.915+%2F+%28+x+%2B+4.5+%29+=+.64+
++3.915+%2F+%28+1.6172+%2B+4.5+%29+=+.64+
+3.915+%2F+6.1172+=+.64+
+.639999+=+.64+
OK -error due to rounding off

Answer by jorel555(1290) About Me  (Show Source):
You can put this solution on YOUR website!
If the water is pure, then it is 100% water. We start out with an 87% acid solution, so:
4.5(.87)+ X(1.0)=.64(4.5+X)
3.915+X=2.88+.64X
1.035=.64X
X=1.035/.64=1.6172 liters of pure water needed to add to the mixture to make it 64% acid!!!!