SOLUTION: A dehydrated patient needs a 6.1% saline IV. Unfortunately the hospital only has bags of 5% and 7% saline solutions. How many liters of each of these solutions should be mixed toge

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: A dehydrated patient needs a 6.1% saline IV. Unfortunately the hospital only has bags of 5% and 7% saline solutions. How many liters of each of these solutions should be mixed toge      Log On


   

Question 371916: A dehydrated patient needs a 6.1% saline IV. Unfortunately the hospital only has bags of 5% and 7% saline solutions. How many liters of each of these solutions should be mixed together to yield 2 liters of the desired concentration?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!

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Let A be the amount of 5% solution, B the amount of 7% solution.
1.A%2BB=2
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5A%2B7B=6.1%282%29
2.5A%2B7B=12.2
Multiply eq. 1 by (-5) and add to eq. 2,
-5A-5B%2B5A%2B7B=-10%2B12.2
2B=2.2
highlight%28B=1.1%29liters
Then from eq. 1,
A%2B1.1=2
highlight%28A=0.9%29liters