Average Workout Duration per Treadmill

PandasEasyJunior level~10 min

Problem

The `treadmill_log` DataFrame has columns `treadmill_id`, `session_id`, `phase`, and `moment`. Each treadmill records two rows per workout session: one with `phase = 'start'` and one with `phase = 'finish'`, where `moment` is the timestamp in seconds.\n\nFor every treadmill, compute the **average workout duration** across all of its sessions. A session's duration is its finish timestamp minus its start timestamp. Round to 3 decimal places, alias the result `avg_duration`, and return one row per treadmill.

Input data

Example rows — the live problem includes the full dataset.

treadmill_log

treadmill_id	session_id	phase	moment
1	10	start	100.0
1	10	finish	130.0
1	11	start	200.0
1	11	finish	250.0
2	12	start	50.0

Expected output

Your answer should return 2 rows with the columns treadmill_id, avg_duration.

Starter code (Pandas (Python))

import pandas as pd

def avg_workout_duration(treadmill_log) -> pd.DataFrame:
    # Your code here
    return treadmill_log

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