What is the stroke volume in a person if his resting cardiac output is 5.25 L/min and heart rate = 75/min?

Options

A. 70
B. 75
C. 80
D. 72

Answer

To find the stroke volume of a person given the resting cardiac output and heart rate, we can use the following formula:

**Cardiac Output (CO) = Heart Rate (HR) × Stroke Volume (SV)**

### Step-by-Step Solution:

1. **Identify the Given Values:**
- Cardiac Output (CO) = 5.25 L/min
- Heart Rate (HR) = 75 beats/min

2. **Convert Cardiac Output to Milliliters:**
- Since 1 L = 1000 mL, we convert 5.25 L to mL:
\[ CO = 5.25 \, \text{L/min} \times 1000 \, \text{mL/L} = 5250 \, \text{mL/min} \]

3. **Use the Formula to Find Stroke Volume:**
- Rearranging the formula to solve for Stroke Volume (SV):
\[ SV = \frac{CO}{HR} \]
- Substitute the values:
\[ SV = \frac{5250 \, \text{mL/min}}{75 \, \text{beats/min}} \]

4. **Calculate Stroke Volume:**
\[ SV = 70 \, \text{mL/beat} \]

5. **Conclusion:**
- The stroke volume of the person is **70 mL/beat**.