How do I find the rate??

shaas, ASN, RN · Dec 3, 2010

Hi, there. I'm writing in step-by-step thought process because I believe that you may need help in solidifying the concept of how to find rates. I apologize for it being longer than a simple formula.

1). The rate they want is in the units of mL/hr (volume/time).

2). The data you're given has both the volume (mL, L, dL, etc.) and time (sec, min, hr, etc.)

3). You have the volume in the desired unit, already. Do you have the time in the unit that the question is asking for? Is minute the same as hour? If no, then how would you convert minute to hour?

*1 hr = 60 min. This can also be expressed as 1 hr/60 min, or 60 min/hr (these are called 'conversion factors'). What goes on top or bottom of the conversion factor only matters on which quantity you want to convert.

For example, if you want to convert 1.5 hr to minutes, you convert as follows:

1.5 hr x (60 min/hr) = 90 min *Pay attention to which unit goes on the bottom and the top of the conversion factor to get to the desired unit of hr.

If you want to convert 44 min to hr, then you'd convert as follows:

44 min x (1 hr/60 min) = 0.73 h *The fraction form is a much better quantitative representation of time than a fraction, 11/15 h (all scientific quantity uses the decimal representation)

So, follow the steps and see if you can find the answer.

4). You should be asking yourself, how many hr is equivalent to 15 min?

5). Now, find the rate as asked (mL/hr), which means plug in the volume given on the top of the numerator, and plug in the hr that you've figured out on (4) on the denominator. That is your rate.

Good luck.

noyesno, MSN, APRN, NP · Dec 4, 2010

You've got:

20 ml

--------

15 mins

Covert the mins to hrs by doing this:

20 ml 60 mins

-------- * --------

15 mins 1 hr

What does that give you?

2ndyearstudent, CNA · Dec 4, 2010

Several semesters ago we learned this stuff but it was on a pre-test today and I could not remember how to set it up!! THANKS!!!!!!
The nurse is preparing to administer a dose of IV Decadron. The med is available in a 20mL IV bag and the nurse wants to administer the med over 15 minutes. At what rate (mL/hr) will the nurse set the pump?

If you were driving a car and went 20 miles in 15 minutes how many miles would you go in an hour?

MunoRN, RN · Dec 5, 2010

Assuming the amount of medication (usually in mg) in the 20ml bag is the the correct dose, you can think of it this way:

You want to give 20ml in 15 minutes, or 20ml per 15 minutes, or 20ml / 15 min. To get the number of mls per hour, you need to take the known ratio (20/15) and find what the mls would be (X) in an equal ratio where the bottom number (minutes) is 60. The easiest way to do this is cross multiply and divide:

20 ....... X

---- = ----

15 ....... 60

20 x 60 =1200, 1200 divided by 15 = 80 ml/hr.

Always make sure that the answer makes sense: If you want to give 20 mls in 15 minutes, then the rate should approx. 4 times the amount you want to give, since 15 minutes in 1/4 of an hour. (If your rate was 800 or 8 for instance you may want to re-check you math).