Respuesta :

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

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