I am confused and need some help with this math question.

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The client with lung cancer is 1 day post-op lobectomy and demonstrates symptoms of infection. The health care provider orders 900 mg of Nafcillin. There is powder in a vial labeled "Nafcillin 1 gram" with instructions "to dilute with 3.4 mL of sterile water to produce 1 gram in 4 mL.".

How many milliliters does the nurse administer? (Round to the nearest tenth and write only the number.)

**please let me know some simple steps on how you got the answer. Maybe i am studying too much and my brain is burning out

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A simple ratio calculation would work here

1000mg/4ml = 900mg/x

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this is what it says :

(4 mL/1 gram) X (1 gram/1000 mg) X (900 mg/1) = 3600/1000 = 3.6 mL

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Yes, that's the answer I got.

To make this really simple, you need to find out how many mg/ml the solution is.

1000mg/4ml equals 250mg/ml

You need 900mg. How many times does 250 go into 900?

900/250= 3.6

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I dont know what is wrong with me sometimes I just cant see it.

one way i was doing it is 900 / 1000 = 0.9 0.9 x 4 = 3.6

another weird way is 900 x 4 = 3600 3600/1000 = 3.6

do you know a website that can help me out with the math? It is tough for me to see it in my mind.

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I am in nursing school at the University of South Florida. We use the book Calculating with Confidence 5th Edition by Gray Morris. The book has a website There is some great info on doing calculations and practice problems. You do need to register.

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Specializes in Acute Care, Rehab, Palliative.

I use Doc (what the doctor ordered) over stock ( what you have on hand) 900/1000 = 0.9.Multiplied by the volume(4) = 3.6

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thanks i will check it out :up:

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Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.

You may find this website helpful.

DosageHelp.com - Helping Nursing Students Learn Dosage Calculations

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Great website! thanks!

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Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.

You're welcome!

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Some simple steps:

1. Don't forget to convert your g to mg.

2. Remember the Mass/Liquid for Liquid Formula (found on site previously posted)

[TABLE]

[TR]

[TD] Ordered[/TD]

[TD] X[/TD]

[TD] Volume have[/TD]

[TD] =[/TD]

[TD] Liquid Required[/TD]

[/TR]

[TR]

[TD] Have[/TD]

[/TR]

[/TABLE]

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