A man travels first 50 km at 25 kmph, next 40 km at 20 kmph and then 90 km at 15 kmph. His average speed for the whole journey (in kmph) is:

Options

A. 25
B. 20
C. 18
D. 40

Answer

To find the average speed of the man for the entire journey, we can follow these steps:

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

1. **First Segment:**
- Distance = 50 km
- Speed = 25 km/h
- Time (T1) = Distance / Speed = 50 km / 25 km/h = 2 hours

2. **Second Segment:**
- Distance = 40 km
- Speed = 20 km/h
- Time (T2) = Distance / Speed = 40 km / 20 km/h = 2 hours

3. **Third Segment:**
- Distance = 90 km
- Speed = 15 km/h
- Time (T3) = Distance / Speed = 90 km / 15 km/h = 6 hours

### Step 2: Calculate the total distance and total time.

- **Total Distance (D)** = 50 km + 40 km + 90 km = 180 km
- **Total Time (T)** = T1 + T2 + T3 = 2 hours + 2 hours + 6 hours = 10 hours

### Step 3: Calculate the average speed.

- **Average Speed (V_avg)** = Total Distance / Total Time = 180 km / 10 hours = 18 km/h

Thus, the average speed for the whole journey is **18 km/h**.

### Final Answer:
The average speed for the whole journey is **18 km/h**.

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