A 210 meres long train crosses a platform of equal length in 20 seconds. What is the speed of the train ?

Options

A. 62.6 km/hr
B. 68.4 km/hr
C. 75.6 km/hr
D. Can't be determind

Answer

To find the speed of the train, we can follow these steps:

### Step 1: Understand the problem
We know that the length of the train is 210 meters and it crosses a platform of equal length (also 210 meters) in 20 seconds.

### Step 2: Calculate the total distance traveled
When the train crosses the platform, it travels a distance equal to the length of the train plus the length of the platform.

Total distance = Length of the train + Length of the platform
Total distance = 210 m + 210 m = 420 m

### Step 3: Calculate the speed of the train
Speed is defined as the distance traveled divided by the time taken.

Speed = Total distance / Time taken
Speed = 420 m / 20 s = 21 m/s

### Step 4: Convert speed from meters per second to kilometers per hour
To convert meters per second to kilometers per hour, we multiply by \( \frac{18}{5} \).

Speed in km/h = Speed in m/s × \( \frac{18}{5} \)
Speed in km/h = 21 m/s × \( \frac{18}{5} \)
Speed in km/h = 21 × 3.6 = 75.6 km/h

### Conclusion
The speed of the train is 75.6 km/h.

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