Final answer:
The average speed for the entire journey of a car that made a round trip of 216 km with speeds of 48 km/h and 72 km/h is 57.6 km/h. This is calculated by finding the total distance (432 km) and dividing it by the total time (7.5 hours) taken for the journey.
Step-by-step explanation:
To calculate the average speed for the whole journey of a car that traveled 216 km at an average speed of 48 km/h on the way there and at 72 km/h on the return, we must first determine the total distance and the total time for the entire trip.
To find the time taken for each leg of the trip, we use the formula:
Time = Distance / Average Speed
- Time for the first leg (to destination) = 216 km / 48 km/h = 4.5 hours
- Time for the second leg (return journey) = 216 km / 72 km/h = 3 hours
- Total time for both legs = 4.5 hours + 3 hours = 7.5 hours
- Total distance for both legs = 216 km + 216 km = 432 km
With the total time and distance, we can now determine the average speed for the entire journey:
Average Speed = Total Distance / Total Time = 432 km / 7.5 h = 57.6 km/h.
Therefore, the average speed for the car's entire trip is 57.6 km/h.