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# Dosage Calculation Test - page 3

I need to take the Dosage test and pass with a 90% We don't even have this test in HI, and I'm not sure what to expect. This is for a school in STL, MO. I tried to look up books online but... Read More

1. I have a practice dosage calculation test and I was able to figure out all of the doses correctly, except for this one: order: Ancef 500mg. available : 1g. directions: reconstitute with 2.5 mL normal saline to yield 3 ml. worth a concentration of 330 mg/ml. I know that the correct answer is 1.5 ml. I set up this proportion to come up with 1.5 ml.I was wondering if this is the correct way!1000 mg/3 ml X 500mg/x ml
2. It's late, I'm heading toward my 3rd 12-hour shift early tomorrow morning, so I'm not sure I'm reading this right, but the way I read it, this is the way I would set up the problem:

Ordered/Available X Volume (I remember by "OAK", Ordered divided by Available times the Quantity)

So, what I'm seeing would be:

500/330 X 1 ml = 1.51 ml (or -- rounding -- 1.5 ml)

I don't do the ratio or dimensional analysis thing too well. Have a miserable time setting up the proportions correctly; they make me DIZZY!!

Use whatever works for you!! And good luck!!
3. You need to ratio and proportions, and the test I just took also threw ina question about grains which was not on the practice test and threw me off of course. Other than that, I would go by the practice test that Meramec offers.
4. Were calculators permitted or did you have to do the multiplication/division manually?
5. Quote from sunchild
I have a practice dosage calculation test and I was able to figure out all of the doses correctly, except for this one: order: Ancef 500mg. available : 1g. directions: reconstitute with 2.5 mL normal saline to yield 3 ml. worth a concentration of 330 mg/ml. I know that the correct answer is 1.5 ml. I set up this proportion to come up with 1.5 ml.I was wondering if this is the correct way!1000 mg/3 ml X 500mg/x ml
I thought you would divide the 500mg by 1g=1000mg and times by the 3ml.

500mg/1000mg =.5 x 3ml =1.5 ml
6. Just wanted to offer some help for people who stumble upon this thread like I did!
I JUST took this test 2 days ago and found out at my nursing advising appointment yesterday that I got 100%
I am self proclaimed "math ignorant" so I figured my first try wouldn't go so well but I wanted to do everything I could on my own before resorting to the nursing math class they offer... so I bought a book called "Math for Nurses" that was put out by Kaplan and read/did the practice problems in there for about a week and that's it.
Know your conversions (including grains to milligrams) and work the problems in this book! It is pretty cheap, about \$15, and shows in detail 3 different techniques for mastering the problems on the test. The one I found easiest is "Dimensional Analysis"

So for this problem: Order : Ancef 500mg. available : 1g. directions: reconstitute with 2.5 mL normal saline to yield 3 ml. worth a concentration of 330 mg/ml.
They give you a lot more information than you need making it look so much more complicated than it is.
Always start with the order (500 mg) then in these problems all you need for the test is the end yield (330mg/ml). Just work it from there like the rest of the problems that don't include reconstitution.
500mg x 1mL / 330 mg
The two mg cancel out so that your answer is in mL and you get 1.5151515 which rounds to 1.5 mL