What is the approximate normal resting cardiac output?

• A. About 3 liters per minute
• B. About 5 liters per minute
• C. About 7 liters per minute
• D. About 10 liters per minute

Answer: (B)

The main idea here is that cardiac output at rest is the product of heart rate and stroke volume. In a typical adult at rest, heart rate is about 60–80 beats per minute and stroke volume around 70 mL per beat. Multiplying those together gives roughly 60 × 70 = 4200 mL/min up to 80 × 70 = 5600 mL/min, so about 4–6 L per minute, with many references citing an average near 5 L/min. That’s why the best answer is around 5 liters per minute.

If a number like 3 L/min were the resting value, it would mean either a much lower heart rate or a much smaller stroke volume than usual at rest. A resting output of 7 L/min is higher than typical resting values and would be more likely seen with increased demand or fitness, while 10 L/min is generally associated with light exercise or much higher metabolic needs.