To determine how long it will take for the train to pass a platform 650 meters long, follow these steps:

1. **Find the speed of the train:**

  The length of the train is 240 meters, and it takes 24 seconds to pass a pole. The speed of the train can be calculated as:

  \[ \text{Speed} = \frac{\text{Distance}}{\text{Time}} \]

  Here, the distance is the length of the train (240 meters) and the time is 24 seconds.

  \[ \text{Speed} = \frac{240 \text{ meters}}{24 \text{ seconds}} \]

  \[ \text{Speed} = 10 \text{ meters/second} \]

2. **Determine the total distance to be covered when passing the platform:**

  The train needs to cover its own length plus the length of the platform to completely pass the platform.

  \[ \text{Total Distance} = \text{Length of the Train} + \text{Length of the Platform} \]

  \[ \text{Total Distance} = 240 \text{ meters} + 650 \text{ meters} \]

  \[ \text{Total Distance} = 890 \text{ meters} \]

3. **Calculate the time required to pass the platform:**

  Using the speed of the train and the total distance, we can find the time required.

  \[ \text{Time} = \frac{\text{Total Distance}}{\text{Speed}} \]

  \[ \text{Time} = \frac{890 \text{ meters}}{10 \text{ meters/second}} \]

  \[ \text{Time} = 89 \text{ seconds} \]

Therefore, it will take the train 89 seconds to pass the platform that is 650 meters long.