# The Late Arrival

> The clock was lying.

Canonical URL: <https://datadriven.io/problems/the_late_arrival>

Domain: AI Coding · Difficulty: easy · Seniority: L4

## Problem

Finance reports the daily orders dashboard is missing roughly 3% of revenue versus the source system of record. Reproduce by running tests/test_late_events.py. Fix the pipeline so the test passes; keep any currently-passing tests green. Be ready to walk an interviewer through what changed and how a re-run on the next hour does or does not double-count.

## Related

- [All practice problems](https://datadriven.io/problems)
- [Mock interview mode](https://datadriven.io/interview/the_late_arrival)
- [Data Engineering Interview Prep Guide](https://datadriven.io/data-engineer-interview-prep)
- [Daily Challenge](https://datadriven.io/daily)

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