An IV line delivers 42 mL/h. How much fluid will the patient receive in 2 hours?

An IV line delivers 42 mL/h. How much fluid will the patient receive in 2 hours?

• A. 84 mL
• B. 42 mL
• C. 168 mL
• D. 100 mL

Answer: (A)

The key idea is that volume equals flow rate multiplied by time. The infusion rate is 42 mL per hour, so in two hours you multiply by 2: 42 × 2 = 84. The hours cancel properly, leaving milliliters. Doubling the time doubles the delivered volume, which matches the calculation. If only one hour passed, you’d have 42 mL; four hours would be 168 mL; 100 mL corresponds to about 2.38 hours, not the two-hour interval in this question.

The key idea is that volume equals flow rate multiplied by time. The infusion rate is 42 mL per hour, so in two hours you multiply by 2: 42 × 2 = 84. The hours cancel properly, leaving milliliters. Doubling the time doubles the delivered volume, which matches the calculation. If only one hour passed, you’d have 42 mL; four hours would be 168 mL; 100 mL corresponds to about 2.38 hours, not the two-hour interval in this question.