A 700 metre long train crosses an 800 metre long bridge in 27 seconds. What is speed (in km/hr) of the train?

Options

A. 180
B. 200
C. 250
D. 175

Answer

To find the speed of the train in km/hr, we can follow these steps:

### Step 1: Calculate the Total Distance
The train crosses the entire length of the bridge plus its own length.
- Length of the train = 700 meters
- Length of the bridge = 800 meters

Total distance = Length of the train + Length of the bridge
\[ \text{Total Distance} = 700 \, \text{m} + 800 \, \text{m} = 1500 \, \text{m} \]

### Step 2: Use the Formula for Speed
Speed is defined as the distance traveled divided by the time taken. The formula is:
\[ \text{Speed} = \frac{\text{Distance}}{\text{Time}} \]

Here, the distance is 1500 meters and the time is 27 seconds.

### Step 3: Calculate Speed in Meters per Second
Using the formula:
\[ \text{Speed} = \frac{1500 \, \text{m}}{27 \, \text{s}} \]
Calculating this gives:
\[ \text{Speed} \approx 55.56 \, \text{m/s} \]

### Step 4: Convert Speed to Kilometers per Hour
To convert meters per second to kilometers per hour, we multiply by 18/5:
\[ \text{Speed in km/hr} = 55.56 \, \text{m/s} \times \frac{18}{5} \]
Calculating this gives:
\[ \text{Speed in km/hr} \approx 200 \, \text{km/hr} \]

### Final Answer
The speed of the train is approximately **200 km/hr**.

---