An intravenous line is delivering fluid at 42 mL/h. How much fluid will the patient receive in 12 hours?

• A. 480 mL
• B. 504 mL
• C. 540 mL
• D. 492 mL

Answer: (B)

Total fluid delivered equals the infusion rate multiplied by the time the line runs. At 42 mL per hour for 12 hours, you calculate 42 × 12 = 504 mL. So the patient would receive 504 mL.

The other numbers come from using a different rate (for example, 40 mL/h × 12 h = 480 mL; 41 mL/h × 12 h = 492 mL) or from altering the time, so they don’t match the given rate and duration.