To calculate Hazel's average speed over the two runs, we need to find the total distance she covered and the total time she spent running.
Step 1: Calculate total distance.
- Distance from last Monday: 5.4 miles
- Distance from last Friday: 4.3 miles
Total distance: \[ 5.4 \text{ miles} + 4.3 \text{ miles} = 9.7 \text{ miles} \]
Step 2: Calculate total time.
- Time from last Monday: 45 minutes
- Time from last Friday: 29 minutes
Total time: \[ 45 \text{ minutes} + 29 \text{ minutes} = 74 \text{ minutes} \]
Step 3: Convert the total time into hours. Since speed is typically measured in miles per hour (mph), we need to convert minutes into hours: \[ 74 \text{ minutes} = \frac{74}{60} \text{ hours} \approx 1.2333 \text{ hours} \]
Step 4: Calculate average speed. Average speed is given by the formula: \[ \text{Average speed} = \frac{\text{Total distance}}{\text{Total time}} \]
Applying the numbers: \[ \text{Average speed} = \frac{9.7 \text{ miles}}{1.2333 \text{ hours}} \approx 7.86 \text{ mph} \]
Step 5: Round the average speed to the nearest tenth. Rounding 7.86 to the nearest tenth gives: \[ \text{Average speed} \approx 7.9 \text{ mph} \]
Thus, Hazel's average speed over the two runs is 7.9 mph.