SOLUTION: A crop dusting service needs to prepare a 0.8% pesticide solution. It has an airplane with a 300-gal tank that contains 100 gal of a 0.5% solution. How much of a previously mixed 1

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Question 1041595: A crop dusting service needs to prepare a 0.8% pesticide solution. It has an airplane with a 300-gal tank that contains 100 gal of a 0.5% solution. How much of a previously mixed 1% pesticide solution should be added to the tank to increase the concentration to the desired 0.8%?
Found 2 solutions by josgarithmetic, josmiceli:
Answer by josgarithmetic(39618) About Me  (Show Source):
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = gallons of 1% solution needed
+.005%2A100+=+.5+ gallons of pure pesticide initially
in the 300 gallon tank
----------------------------
+%28+.01x+%2B+.5+%29+%2F+%28+x+%2B+100+%29+=+.008+
+.01x+%2B+.5+=+.008%2A%28+x+%2B+100+%29+
+.01x+%2B+.5+=+.008x+%2B+.8+
+.002x+=+.3+
+x+=+150+
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150 gallons of 1% solution needs to be added
check:
+%28+.01%2A150+%2B+.5+%29+%2F+%28+150+%2B+100+%29+=+.008+
+%28+1.5+%2B+.5+%29+%2F+250+=+.008+
+2+%2F+250+=+.008+
+.008+=+.008+
OK