A train 150 m long passes a telegraph post in 12 seconds. Find in what time, it will pass a bridge 250 m long ?

Options

A. 32 sec
B. 36 sec
C. 25 sec
D. 24 sec

Answer

To solve the problem step by step, we will follow these calculations:

### Step 1: Determine the speed of the train
The length of the train is given as 150 meters, and it passes a telegraph post in 12 seconds.

**Formula for speed:**
\[ \text{Speed} = \frac{\text{Distance}}{\text{Time}} \]

**Calculation:**
\[ \text{Speed} = \frac{150 \text{ m}}{12 \text{ s}} = 12.5 \text{ m/s} \]

### Step 2: Calculate the total distance to be covered when passing the bridge
The length of the bridge is given as 250 meters. When the train passes the bridge, it has to cover its own length plus the length of the bridge.

**Total Distance:**
\[ \text{Total Distance} = \text{Length of Train} + \text{Length of Bridge} \]
\[ \text{Total Distance} = 150 \text{ m} + 250 \text{ m} = 400 \text{ m} \]

### Step 3: Calculate the time taken to pass the bridge
Now we will use the speed we calculated in Step 1 to find the time taken to pass the bridge.

**Formula for time:**
\[ \text{Time} = \frac{\text{Distance}}{\text{Speed}} \]

**Calculation:**
\[ \text{Time} = \frac{400 \text{ m}}{12.5 \text{ m/s}} \]

Now, performing the division:
\[ \text{Time} = 32 \text{ seconds} \]

### Final Answer
The train will take 32 seconds to pass the bridge.

---