Excluding stoppages, the speed of a train is 45 km/hr and including stoppages it is 36 km/hr. For how many minutes does the train stop per hour?

Options

A. 10
B. 12
C. 15
D. 18

Answer

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

### Step 1: Identify the speeds
- The speed of the train excluding stoppages = 45 km/hr
- The speed of the train including stoppages = 36 km/hr

### Step 2: Calculate the difference in speed
- The difference in speed due to stoppages = 45 km/hr - 36 km/hr = 9 km/hr

### Step 3: Calculate the time taken to cover the distance lost due to stoppages
- The distance lost due to stoppages is 9 km (the difference in speed).
- We need to find the time taken to cover this distance at the speed of 45 km/hr.

### Step 4: Use the formula for time
- Time = Distance / Speed
- Here, Distance = 9 km and Speed = 45 km/hr
- Time = 9 km / 45 km/hr = 1/5 hour

### Step 5: Convert time from hours to minutes
- Since 1 hour = 60 minutes, we convert 1/5 hour to minutes:
- Time in minutes = (1/5) * 60 = 12 minutes

### Conclusion
- Therefore, the train stops for **12 minutes** per hour.

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