An aerplane covers 2500 km,1200 km and 500 km at the rate of 500 km/hr ,400 km/hr and 250 km/hr respectively .Find its average speed for the whole journey.

Answer

To find the average speed of the airplane for the whole journey, we will follow these steps:

### Step 1: Calculate the time taken for each segment of the journey.

1. **First Segment:**
- Distance = 2500 km
- Speed = 500 km/hr
- Time = Distance / Speed = 2500 km / 500 km/hr = 5 hours

2. **Second Segment:**
- Distance = 1200 km
- Speed = 400 km/hr
- Time = Distance / Speed = 1200 km / 400 km/hr = 3 hours

3. **Third Segment:**
- Distance = 500 km
- Speed = 250 km/hr
- Time = Distance / Speed = 500 km / 250 km/hr = 2 hours

### Step 2: Calculate the total distance covered.

- Total Distance = 2500 km + 1200 km + 500 km = 4200 km

### Step 3: Calculate the total time taken.

- Total Time = 5 hours + 3 hours + 2 hours = 10 hours

### Step 4: Calculate the average speed.

- Average Speed = Total Distance / Total Time = 4200 km / 10 hours = 420 km/hr

### Final Answer:
The average speed of the airplane for the whole journey is **420 km/hr**.

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