math question

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Hi all

This is greatgoku. I'm a 3rd semester nursing student with a big math test coming up. I only get 2 trys to pass it or im kicked out. The thing i'm worried about is my teacher gave us guidelines on things we need to know. He said "KNOW HOW TO CALCULATE HOW MANY MG IT TAKES TO MAKE A CERTAIN 'PERCENTAGE' OF A SOLUTION". I have no idea what he is talking about. I was hoping someone from the nursing world can help me figure it out. I thought it would be like 486mg are ordered, the pt lost weight so its now 20percent of the original. But that has nothing to do with a solution. So im really stumped right now. The test is wed. If anyone has any idea and have the time to leave a message what these problems are and how to work it out, it would be much appreciated. Thanks for taking the time to read this.

greatgoku ~ John

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Specializes in med/surg, telemetry, IV therapy, mgmt.

hi, greatgoku81, and welcome to allnurses! :welcome:

i think that perhaps what your teacher is getting at is giving you problems like this:

how many
milli
grams of dextrose will it take to make a one liter solution of 5% dextrose in water? [this, by the way, is a problem grounded in real fact and a very similar type of question was on my state
rn
licensing examination 30+ years ago.]

answer: 50
milli
grams of dextrose. you must convert liters to a similar unit of
milli
liters and multiply it by 5% to come up with the 50
milli
gram answer.

how many
milli
grams of xxx drug is needed to make 50
milli
liters of a 2% solution?

50 ml x 0.02 = 1 mg

this is basic pre-algebra and you have to be mindful of the "labels" that go along with the numbers you are working with as well. we have listings of tutorials in basic math and algebra where you can get review in ratio and percentages on allnurses. they are listed on post #3 of this sticky thread:

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