I walked for 2 1/2 hours at 4km/h and for 4 hours at 2 1/2 km/h. What was the average speed for the entire journey?

Average speed of the entire journey is 3.08 km/hr

Step-by-step explanation:

Step 1: In the first half, given that the speed = 4 km/h and time = 2 1/2 = 2.5 hrs. Calculate the distance covered.

Distance = Speed * Time = 4 * 2.5 = 10 km

Step 2: In the second half, given that speed = 2 1/2 = 2.5 km/hr and time = 4 hrs. Calculate the distance covered.

Distance = 2.5 * 4 = 10 km

Step 3: Calculate average speed.

Average Speed = Total distance/Total time

= 10 + 10/2.5 + 4 = 20/6.5

= 3.08 km/hr