[Li-Zhuo-Ran]

Summary

• Reviewed the Pandas data analysis lecture against the English source.
• Clarified that population values reported in thousands are converted back to individual persons.
• Preserved all code, equations, figures, exercises, and solutions.

Validation

• git diff --check
• Code-cell, figure, image, exercise, solution, note, and code-block counts match the English source.

Refs #88