Med Math: Drop Factors Question #10


The same IV orders above (1000 mL over 8 hours for 125 mL/hr) has infused for 4 hours. How many mL is left in the bag?


  1. 250 mL
    • Rationale:
  2. 500 mL
    • Rationale:
  3. 125 mL
    • Rationale:
  4. 300 mL
    • 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 total volume is set at 1000 ml to be infused. The D5.45 NS is extra information and not needed to solve the problem. The hour is not converted to minutes to solve the problem. The 1000 ml to be infused is divided by 8 hours. There is a simple formula below for calculating the flow rate.Then the volume left needs to be calculated. If 1000 ml is the total and 500 ml was infused you would have 500 left. The final answer should have ml within.

ML/Hr x Hr = Total volume infused so far

Total Volume is set for required time subtracted by infused volume= Volume left to be infused

Total volume_1000 ml_ – infused volume__500 ml = _500___ ML left to infuse

125 mL/h x 4 h = 500 mL infused so 500 mL is left in the bag

Learning Outcomes

Test Taking Tip

Video Rationale