Final answer:
To find the average velocity, calculate the distances covered at each speed, sum them to get the total distance, then divide by the total time. The average velocity in this scenario is 57.5 km/h, which rounds to 57 km/h, answer B.
Step-by-step explanation:
To calculate the average velocity of a car that drives 9 hours at 48 km/h and then another 9 hours at 67 km/h, you can use the formula for average velocity, which is the total distance travelled divided by the total time taken.
Firstly, find the distances covered at each speed:
- Distance at 48 km/h = 48 km/h × 9 h = 432 km
- Distance at 67 km/h = 67 km/h × 9 h = 603 km
Next, calculate the total distance and total time:
- Total distance = 432 km + 603 km = 1035 km
- Total time = 9 h + 9 h = 18 h
Finally, divide the total distance by the total time:
Average velocity = Total distance / Total time = 1035 km / 18 h = 57.5 km/h
Therefore, the correct answer is B) 57 km/h.