# Med Math Help

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The patient is ordered levofloxacin 750 mg in 150 ml of d5w to infuse over 90 minutes. The client weighs 150lbs. Calculate the dosage in ml/hr.

2 Articles; 127 Posts

Specializes in Pharmacy, Mathematics, Physics, and Educator. Has 30+ years experience.

The only thing that matters is the 150 mL over 90 minutes. See if you can change that to mL/h.

414 Posts

Specializes in Psychiatry. Has 8 years experience.

(150/90) x (60/1)

Rate is ml/hour

1 hour is 60 minutes. In this example you have 90 minutes and not 60. 150 (rate) / 90 (time)

2 Articles; 127 Posts

Specializes in Pharmacy, Mathematics, Physics, and Educator. Has 30+ years experience.

So just to be technically clear, you are starting with 150 mL/90 min and have to end up with mL/h. You will multiply by 60 min/h. Min will cancel out leaving 100 mL/h.

262 Posts

Specializes in CEN | CCRN | ED and CICU. Has 5 years experience.

Always read what the question is asking you to solve for. Skip the beginning so you don't confuse yourself with the distractors.

For this example, you are solving for mL per hour or mL/hr. Now read the entire question.

Now set up the equation in the order of what you are solving for (mL on top hr on bottom) with this being the first part of your equation.

So: 150mL OVER 90 minutes (150mL/90 mins)...get rid of mins and convert to hr.

150mL/90 mins x 60 mins/hr = 150 ml/90 x 60/hr = 9000 mL/90hr = 100 mL/hr

1,578 Posts

Specializes in 15 years in ICU, 22 years in PACU. Has 30 years experience.
Always read what the question is asking you to solve for. Skip the beginning so you don't confuse yourself with the distractors.

For this example, you are solving for mL per hour or mL/hr. Now read the entire question.

Now set up the equation in the order of what you are solving for (mL on top hr on bottom) with this being the first part of your equation.

So: 150mL OVER 90 minutes (150mL/90 mins)...get rid of mins and convert to hr.

150mL/90 mins x 60 mins/hr = 150 ml/90 x 60/hr = 9000 mL/90hr = 100 mL/hr

It's usually most helpful to ask what the student already knows. How have they tried to solve the problem rather than just to solve it for them.

13 Posts

Thanks so much everyone for your help! I was distracted by the 750 mg. I kept trying to fit it into the calculation

5,879 Posts

It's usually most helpful to ask what the student already knows. How have they tried to solve the problem rather than just to solve it for them.

I agree. I really think it should be a TOS violation to just give someone the answer to a question.

This is a pretty good example of how "help" should go:

https://allnurses.com/general-nursing-student/i-cant-figure-1168609.html

678 Posts

Giving them the answer but walking them through how it's done is a good way to teach them how to do it though. Then knowing the answer, they can always go back and see if they're doing it right because they know what the answer should be.

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