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preloaded fixtures
import pandas as pd
import numpy as np
usage = pd.DataFrame({
"user_id": [1, 1, 2, 2, 3, 3, 4, 4, 5, 5],
"app": ["FitTrack", "FitTrack", "PixelQuest", "PixelQuest", "NoteVault", "FitTrack", "PixelQuest", "MindCalm", "BudgetBee", "BudgetBee"],
"day": ["2024-03-01", "2024-03-02", "2024-03-01", "2024-03-03", "2024-03-02", "2024-03-04", "2024-03-02", "2024-03-05", "2024-03-01", "2024-03-06"],
"minutes": [22, 14, 65, 40, 11, 30, 9, 25, 7, 18],
"crashes": [0, 1, 2, 0, 0, 0, 3, 1, 0, 0],
})
usage["day"] = pd.to_datetime(usage["day"])
receipts = pd.DataFrame({
"user_id": [1, 1, 2, 3, 4, 5, 5, 6],
"app": ["FitTrack", "PixelQuest", "PixelQuest", "NoteVault", "FitTrack", "BudgetBee", "PixelQuest", "MindCalm"],
"amount": [9.99, 4.99, 19.99, 2.99, 9.99, 6.00, 14.99, 12.50],
"country": ["USA", "USA", "UK", "USA", "Germany", "USA", "USA", "UK"],
})
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“Crash rate per app”
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Pro problem
“Crash rate per app”
This is one of the real interview questions in Pro. Try Pro free for 7 days to unlock it and everything below:
- 293 interview-grade problems across SQL, Python & pandas
- 104+ real-world SQL problems: SaaS retention, fintech ledgers, supply chain, recursive CTEs
- 18 company interview packs (Amazon, Meta, Google, Uber and more)
- AI "explain my mistake" tutor and mock interviews
- Use QueryLab inside Claude, Cursor & other AI assistants
// built for real interview rounds
Practice the patterns 18 top companies test
329 problems · 36 free forever · 293 unlocked with Pro
Card required. Then $12/month. Cancel before your trial ends and you pay nothing.
or keep practicing free problems →Secure checkout by Paddle · instant access · cancel anytime from your account