A train travels 540km at an average speed of 30km/h. On the return journey the average speed is doubled to 60km/h. The average speed of the entire journey is?
We can use the formula:
Average speed = Total distance / Total time
Let's first calculate the total time taken for the entire journey.
Time taken for the first part of the journey = Distance / Speed = 540 / 30 = 18 hours
Time taken for the return journey = Distance / Speed = 540 / 60 = 9 hours
Total time taken for the entire journey = 18 + 9 = 27 hours
Now, let's calculate the total distance covered in the entire journey.
Total distance = Distance in one direction + Distance in the opposite direction
Total distance = 540 + 540 = 1080 km
Using the formula,
Average speed = Total distance / Total time
Average speed = 1080 / 27 = 40 km/h
Therefore, the average speed of the entire journey is 40 km/h.