SOLUTION: In the lab Robbie has two solutions that contain alcohol and is mixing them with each other. He uses 500 mm less of solution A than solution B. Solution A is 20% alcohol in solu

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Question 1048233: In the lab Robbie has two solutions that contain alcohol and is mixing them with each other. He uses 500 mm less of solution A than solution B. Solution A is 20% alcohol in solution B is 13% alcohol. How many millimeters of solution A does he use, if the resulting mixture has 362 mm pure alcohol
Found 2 solutions by ewatrrr, stanbon:
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
Note: (% of pure alcohol)x (the amount of solution) gives one the amount of pure alcohol
Mixing
A + B = 362 pure alcohol
.20(x-500) + .13x = 362
.33x = 462
x = 1400mm, amount of solution B
Solution A = 900mm

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
In the lab Robbie has two solutions that contain alcohol and is mixing them with each other. He uses 500 mm less of solution A than solution B. Solution A is 20% alcohol in solution B is 13% alcohol. How many millimeters of solution A does he use, if the resulting mixture has 362 mm pure alcohol
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B - A = 500 mm
0.13B + 0.20A = 362 mm
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Modify for elimination::
13B - 13A = 13*500
13B + 20A = 100*362
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Add and solve for "A:
7A = 6500 + 36200
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A = 6100 mm (amt. of solution A to use)
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Cheers,
Stan H.
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