Explanation:

- A 480 m long train travels at 90 kmph.

- It crosses another train moving at 144 kmph in 9 seconds.

- To find the length of the second train, convert speeds into meters per second:

- 90 kmph = 25 m/s

- 144 kmph = 40 m/s

- Relative speed = 25 + 40 = 65 m/s.

- Total distance covered in the crossing = 65 m/s * 9 s = 585 m.

- Length of the second train = 585 m - 480 m = 105 m.

- Second train crosses a platform in 8 seconds at 40 m/s.

- Distance covered in 8 seconds = 40 m/s * 8 = 320 m.

- Length of the platform = 320 m - 105 m = 215 m.

- The correct option is Option 3, 215 m .

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