SOLUTION: 2. A chemist wants to make 4 liters of a 7% acid solution by mixing a 10% acid solution and a 4% acid solution. How many liters of each solution should the chemist use? Write your

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Question 927293: 2. A chemist wants to make 4 liters of a 7% acid solution by mixing a 10% acid solution and a 4% acid solution. How many liters of each solution should the chemist use? Write your answer as a complete sentence.
Be sure to:
• Define your variable and expressions for the quantities.
• Write an equation that models the problem.
• Solve the equation.
• State the answer in a complete sentence.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
To do this with just 1 unknown:
Let +x+ = liters of 10% acid solution needed
+4+-+x+ = liters of 4% acid solution needed
--------------------
+%28+.1x+%2B+.04%2A%28+4+-+x+%29+%29+%2F+4+=+.07+
++.1x+%2B+.04%2A%28+4+-+x+%29+=+4%2A.07+
+.1x+%2B+.16+-+.04x+=+.28+
+.06x+=+.12+
+x+=+2+
+4+-+x+=+2+
---------------
2 liters of 10% acid solution are needed
2 liters of 4% acid solution are needed
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check:
+%28+.1x+%2B+.04%2A%28+4+-+x+%29+%29+%2F+4+=+.07+
+%28+.1%2A2+%2B+.04%2A%28+4+-+2+%29+%29+%2F+4+=+.07+
+%28+.2+%2B+.08+%29+%2F+4+=+.07+
+.28+=+.07%2A4+
+.28+=+.28+
OK