Med Math: Drop Factors Question #13


Order for 500 mL of 0.45 NS is to infuse over 8 hours. Calculate the flow rate.


  1. 52 mL/hr
    • Rationale:
  2. 63 mL/hr
    • Rationale:
  3. 100 mL/hr
    • Rationale:
  4. 75 mL/hr
    • Rationale:



Normal Saline is to be infused. You would need to know how much volume in ml you need per hour in order to solve. The 0.45 NS is extra information and not needed to solve the problem. The total volume is set at 500 ml to be infused. The hour is not converted to minutes to solve the problem. The 500 ml to be infused is divided by 8 hours. There is a simple formula below for calculating the flow rate. The final answer should have ml/hr within and rounded up. The reason is that an IV pump rate can not be set at half ml increments but needs to be set at whole ml increments.


—– x 1 (understood to be 1 as in 1 hour)


500 mL/ 8 hrs = 62.5 mL/hr round up! Answer = 63 mL/hr

Learning Outcomes

Test Taking Tip

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