Answer:
70.8 km/h.
Step by step solved:
To find the speed for the whole journey, we need to find the total distance traveled and the total time taken, and then divide the distance by the time.
Let's start by calculating the distance traveled during each leg of the journey:
Distance traveled on foot = speed x time = 60 km/h x 40/60 h = 40 km
Distance traveled in minibus = speed x time = 80 km/h x 2 h = 160 km
Distance traveled on bus = speed x time = 60 km/h x 1 h = 60 km
Now let's add up the distances to find the total distance traveled:
Total distance traveled = 40 km + 160 km + 60 km = 260 km
To find the total time taken, we need to add up the times for each leg of the journey:
Total time taken = 40/60 h + 2 h + 1 h = 3.67 h
Finally, we can divide the total distance by the total time to find the average speed for the whole journey:
Average speed = total distance / total time = 260 km / 3.67 h ≈ 70.8 km/h
Therefore, the man's speed for the whole journey is approximately 70.8 km/h.