Each of the following question is followed by two statements I, and Il. You have to study the question and the statements and decide which of the statement(s) is/are necessary to answer the question.
What is the speed of train (in kmph)?
Statement I: the train crosses a person walking in same direction in 10 sec.
Statement II: The train crosses a 200 m long platform in 20 sec,

Options

A. Only Statement I alone.
B. Only Statement II alone.
C. Both Statements I and II together.
D. Neither Statement I nor II is sufficient

Answer

To determine the speed of the train in kilometers per hour, we will analyze the two statements provided and see which one is necessary to answer the question.

### Step 1: Analyze Statement I
- **Statement I**: The train crosses a person walking in the same direction in 10 seconds.
- Here, we know the time taken to cross a person, but we do not have the distance covered by the train while crossing that person.
- Since speed is calculated as distance divided by time (Speed = Distance/Time), we cannot determine the speed of the train with this statement alone.

**Conclusion from Step 1**: Statement I alone is not sufficient to answer the question.

### Step 2: Analyze Statement II
- **Statement II**: The train crosses a 200 m long platform in 20 seconds.
- In this case, we have both the distance (200 meters) and the time (20 seconds) provided.
- We can calculate the speed of the train using the formula:
\[ \text{Speed} = \frac{\text{Distance}}{\text{Time}} = \frac{200 \text{ meters}}{20 \text{ seconds}} = 10 \text{ meters per second} \]
- To convert this speed into kilometers per hour, we use the conversion factor (1 m/s = 3.6 km/h):
\[ 10 \text{ m/s} \times 3.6 = 36 \text{ km/h} \]

**Conclusion from Step 2**: Statement II alone is sufficient to answer the question.

### Final Conclusion
- **Statement I** is not sufficient to determine the speed of the train.
- **Statement II** is sufficient to determine the speed of the train.
- Therefore, the answer is that only Statement II is necessary to answer the question.