What is the speed of train ?
I Length of train is 120 m.
II It crosses an another train of length 180 m, in 4 s .

Options

A. the statement I alone is sufficient to answer the question but the statement II alone is not sufficient
B. the statement II alone is sufficient to answer the question but the statement I alone is not sufficient
C. both statements I and II together are needed to answer the question
D. cannot get the answer from the statements I and II together and need even more data

Answer

To solve the problem of finding the speed of the train, we can break it down into steps based on the information provided:

### Step 1: Identify the lengths of the trains
- The length of the first train (Train 1) is given as \( L_1 = 120 \) meters.
- The length of the second train (Train 2) is given as \( L_2 = 180 \) meters.

### Step 2: Calculate the total length to be crossed
- When the first train crosses the second train, it covers the combined length of both trains.
- Total length to be crossed = \( L_1 + L_2 = 120 \, \text{m} + 180 \, \text{m} = 300 \, \text{m} \).

### Step 3: Use the time taken to cross
- The time taken to cross the second train is given as \( t = 4 \) seconds.

### Step 4: Set up the equation for speed
- The speed of the train can be calculated using the formula:
\[ \text{Speed} = \frac{\text{Total Length}}{\text{Time}} = \frac{300 \, \text{m}}{4 \, \text{s}}. \]

### Step 5: Calculate the speed
- Now, we can perform the calculation:
\[ \text{Speed} = \frac{300}{4} = 75 \, \text{m/s}. \]

### Conclusion
- The speed of the train is \( 75 \, \text{m/s} \).