DS Practice
FreeFree forever. SQL and Python need no account; other modules need a free login.
754 free interview questions across SQL, Python, stats, ML, and more — with progressive hints, model solutions, and drills that target your weakest areas.
What Is This?
DS Practice is a free interview practice library for data science and analytics roles — 754 questions across 8 modules: SQL, Python, Statistics, A/B Testing, Metrics, Machine Learning, Behavioral, and System Design. It's built for honest practice: you struggle first (hints come one at a time), self-assess honestly (got it, partially, or missed), and drill exactly where you're weak. It's our gift to the DS community — no trial, no credits, no card.
How to Use
Pick a module and difficulty
Go to prepmyrez.com/practice and choose from 8 modules. Within each, pick a difficulty and subtopic — or hit 'mixed random 10' for a surprise set.
Attempt before you peek
Work the question in your head, on paper, or in your own editor. Stuck? Reveal Hint 1, then Hint 2 if you need it. Only then look at the full solution.
Grade yourself honestly
After seeing the solution, mark yourself: got it, partially got it, or missed it. Nobody sees this but you — so lying only cheats your future self.
Review and drill
At the end of a session you'll see a summary of how you did. Use Review Missed to re-attempt questions you bombed, or run the weakest-area drill to target the subtopic you keep missing.
Try timed mode when you're ready
Pick a 10, 20, or 45-minute timed session to practice under pressure — closer to how a real interview feels.
Click any step to see more details
What to Expect
- 754 questions, 8 modules, 3 difficulty levels each
- Every question has 2 progressive hints and a full solution with interviewer notes
- Progress is saved on your device — it works even while logged out
- Session summaries, Review Missed, weakest-area drills, and timed modes
Good to Know
- This is a static question library with self-assessment, not a live AI interviewer. For voice-to-voice practice with feedback, use the AI Interview Simulation (Catalyst Plus).
- Your progress lives in your browser's local storage — clearing browser data resets it.
Tips & Common Mistakes
Actually attempt every question before revealing hints. Reading solutions feels productive; retrieving answers builds skill. They are not the same thing.
Use the interviewer notes — they teach you what a strong answer signals, not just the correct output.
Run the weakest-area drill the day after a session, not immediately. Struggle + sleep + retry is how retention works.
Behavioral module pairs well with the AI Interview Simulation — practice stories here, deliver them there.
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