feel silly asking this question but can someone walk me through this

Cuddleswithpuddles · Mar 6, 2012

Is 40 mg the total amount in the vial?

I think it would be easier if you focused on 2 mg/mL.

Check any dosage calculation book for methods for solving like cross multiplication and dimensional analysis.

It would be more helpful to you to give the problem a trial run instead of simply asking for the answer and an explanation after the fact. Show your method and line of thinking. It will help other people here see where you are getting confused.

tsm007 · Mar 7, 2012

I think the biggest thing when you are reading problems like this is looking at what you need to solve the problem and which numbers are in there that you don't need. As the poster above posted the 2mg/ml is the part you need to know to solve the problem. The 40 mg is just unneeded to solve the problem. It does provide information, just not what you need to set up the equation. If math is a weak area then you are going to work harder on looking at the problem to see what numbers you need to set up your equation.

allnurses Guide · Mar 7, 2012

As mentioned, you really need to try and work through these questions as they will be a big part of your future. If you have put the effort in and are lost, here are some simple tips.

Always set up your calculations (or dimensional analysis is the fancy word for it) so the units you need in the answer are the only ones left when you cancel out. In this case, you want your answer in ml. Set ml as the first number in your calc: start with 1ml/2mg.

You now need to cancel out the mg on the bottom. What information do you have that's in mg? There are two potential numbers to pick: the 20mg the doctor ordered (dose) and the 40mg in the vial (vial size). Which one is important for the question?

Multiply the mg by the 1ml/2mg you started with and you have your answer.

MOST IMPORTANT: Look at your answer and see if it makes sense!