SOLUTION: A nurse has two solutions that contain different concentrations of a certain medication. One is a 25% concentration and the other is a 10% concentration. How many millimeters (ml)

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Question 1142915: A nurse has two solutions that contain different concentrations of a certain medication. One is a 25% concentration and the other is a 10% concentration. How many millimeters (ml) of each should she mix to obtain 20ml of a 16% concentration?
Found 2 solutions by Alan3354, greenestamps:
Answer by Alan3354(69443) (Show Source):
You can put this solution on YOUR website!
A nurse has two solutions that contain different concentrations of a certain medication. One is a 25% concentration and the other is a 10% concentration. How many millimeters (ml) of each should she mix to obtain 20ml of a 16% concentration?
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t = amount of 25%
n = amount of 10%
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25t + 10n = 20*16 ----- total med
t + n = 20 ------------ total solution

Answer by greenestamps(13200) (Show Source):
You can put this solution on YOUR website!

Short, quick path to the answer without formal algebra (for this or any of a number of similar "mixture" problems:

16%is 6/15 = 2/5 of the way from 10% to 25% (10 to 25 is 15; 10 to 16 is 6; 6/15 = 2/5);
Therefore 2/5 of the mixture must be the 25% concentration.

ANSWER: 2/5 of 20ml, or 8ml, of 25%; 12ml of 10%.