### Correct Option: A. 75 km/h #### Step-by-Step Explanation: 1. **Understanding Average Speed**: - Average speed is defined as the total distance traveled divided by the total time taken. It gives us a measure of how fast something is moving over a specific period. 2. **Identifying the Given Values**: - **Distance traveled**: 150 kilometers - **Time taken**: 2 hours 3. **Using the Average Speed Formula**: - The formula for average speed (v) is: \[ v = \frac{\text{Total Distance}}{\text{Total Time}} \] - Plugging in the values: \[ v = \frac{150 \text{ km}}{2 \text{ h}} \] 4. **Performing the Calculation**: - Now, we perform the division: \[ v = 75 \text{ km/h} \] - This means the car traveled at an average speed of 75 kilometers per hour. 5. **Conclusion**: - Therefore, the average speed of the car during this trip is **75 km/h**. #### Why Other Options Are Incorrect: - **Option B: 150 km/h**: - This option suggests that the car traveled 150 kilometers in just 1 hour. However, the problem states that the car took 2 hours to travel 150 kilometers. Thus, this option is incorrect. - **Option C: 300 km/h**: - This option implies an unrealistically high speed, suggesting that the car would cover 300 kilometers in 1 hour. Given the distance and time provided, this is not possible. Therefore, this option is also incorrect. - **Option D: 60 km/h**: - This option suggests a lower average speed than what was calculated. If the car were traveling at 60 km/h, it would take longer than 2 hours to cover 150 kilometers. Specifically, it would take: \[ \text{Time} = \frac{150 \text{ km}}{60 \text{ km/h}} = 2.5 \text{ hours} \] - Since the car only took 2 hours, this option is incorrect. #### Common Pitfalls: - **Misunderstanding Average Speed**: Students sometimes confuse average speed with instantaneous speed, which can lead to incorrect calculations. - **Incorrectly interpreting the time**: It’s crucial to ensure that the time used in calculations matches the distance traveled. - **Forgetting units**: Always ensure that the units are consistent (e.g., kilometers and hours) when calculating speed. ### Revision Summary: - Average speed is calculated as total distance divided by total time. - For this problem, the average speed is 75 km/h, calculated from 150 km in 2 hours. - Other options are incorrect due to miscalculations or unrealistic speeds based on the given distance and time. - Always check units and ensure clarity in understanding average versus instantaneous speed.