An IV bag contains 1000 mL to be infused over 12 hours. What is the infusion rate in mL/hour (rounded to one decimal place)?

• A. 80.0 mL/hr
• B. 83.3 mL/hr
• C. 90.0 mL/hr
• D. 100.0 mL/hr

Answer: (B)

Infusion rate is determined by dividing the total volume to be infused by the total infusion time. For 1000 mL over 12 hours, 1000 ÷ 12 = 83.333... mL/hour. Rounded to one decimal place, that’s 83.3 mL/hour. This rate delivers about 83.3 × 12 ≈ 999.6 mL in 12 hours, effectively 1000 mL. Rates like 80 mL/hr would deliver ~960 mL in 12 hours, while 90 mL/hr would deliver ~1080 mL, and 100 mL/hr would deliver ~1200 mL, which don’t match the required 12-hour window. The correct rate is 83.3 mL/hour.