Data Scientist Interview Questions
Practice 2,964 real Data Scientist interview questions for 2026. Data Scientist interview questions drawn from Meta, Capital One, Amazon, Google, TikTok and similar employers — real questions from actual interviews with detailed solutions — designed to accelerate your interview preparation for product analytics, ML and production data roles. This collection emphasizes the practical skills interviewers test: SQL and data manipulation, experiment design and A/B testing, statistical reasoning, Python coding for data problems, model evaluation and feature engineering, plus machine-learning system tradeoffs and metric design. What’s distinctive about modern data-science loops is the blend of product thinking and reproducible ML: expect hands-on SQL tasks and funnel analysis in screens, deeper experiment-design and causality questions in mid rounds, and coding or modeling challenges plus ML-system discussions in senior loops. Interviewers evaluate problem framing, statistical rigor, and how you communicate decisions to product partners. To prepare, prioritize daily SQL practice (CTEs, window functions), refresh hypothesis-testing and power calculations, rehearse concise metric-driven narratives, and build a few end-to-end model or experiment stories you can explain clearly under time pressure.
"I got asked a hardcore MCM DP question and I saw it on PracHub as well. Solved that question in 5 minutes. Without PracHub I doubt I could solve it in 5 hours. Though somehow didn't get hired, perhaps I guess I solved it too fast? /s"
"Believe me i'm a student here jn US. Recently interviewed for MSFT. They asked me exact question from PracHub. I saw it the night before and ignored it cause why waste time on random sites. I legit wanna go back and redo this whole thing if I had chance. Not saying will work for everyone but there is certainly some merit to that website. And i'm gonna use it in future prep from now on like lc tagged"
"10 years of experience but never worked at a top company. PracHub's senior-level questions helped me break into FAANG at 35. Age is just a number."
"I was skeptical about the 'real questions' claim, so I put it to the test. I searched for the exact question I got grilled on at my last Meta onsite... and it was right there. Word for word."
"Got a Google recruiter call on Monday, interview on Friday. Crammed PracHub for 4 days. Passed every round. This platform is a miracle worker."
"I've used LC, Glassdoor, and random Discords. Nothing comes close to the accuracy here. The questions are actually current — that's what got me. Felt like I had a cheat sheet during the interview."
"The solution quality is insane. It covers approach, edge cases, time complexity, follow-ups. Nothing else comes close."
"Legit the only resource you need. TC went from 180k -> 350k. Just memorize the top 50 for your target company and you're golden."
"PracHub Premium for one month cost me the price of two coffees a week. It landed me a $280K+ starting offer."
"Literally just signed a $600k offer. I only had 2 weeks to prep, so I focused entirely on the company-tagged lists here. If you're targeting L5+, don't overthink it."
"Coaches and bootcamp prep courses cost around $200-300 but PracHub Premium is actually less than a Netflix subscription. And it landed me a $178K offer."
"I honestly don't know how you guys gather so many real interview questions. It's almost scary. I walked into my Amazon loop and recognized 3 out of 4 problems from your database."
"Discovered PracHub 10 days before my interview. By day 5, I stopped being nervous. By interview day, I was actually excited to show what I knew."
"I recently cleared Uber interviews (strong hire in the design round) and all the questions were present in prachub."
"The search is what sold me. I typed in a really niche DP problem I got asked last year and it actually came up, full breakdown and everything. These guys are clearly updating it constantly."
Design profit evaluation for loyalty program
Loyalty Program Incremental Profit Evaluation Plan Context A national grocery chain launched a free loyalty card on January 1. You have 18 months of h...
Present and critique an airline delay analysis
Predicting Airline Departure Delays — Technical Screen Prompt Context You have 15 minutes to review a slide deck on predicting airline departure delay...
Implement scalable prime generator
Write a function first_n_primes(n) that returns the first n prime numbers in ascending order. Constraints: - 1 ≤ n ≤ 100,000. - Aim for O(n log log n)...
Implement minimum window substring with counts
Implement min_window_with_counts(s, t) Task Write a function: - min_window_with_counts(s: str, t: str) -> tuple[int, int] that returns the inclusive (...
Optimize threshold using confusion matrix and costs
Calibrated Classifier on an Imbalanced Dataset (1% positives) You have a perfectly calibrated binary classifier evaluated on 10,000 held-out examples....
Find common friends from directed edges
You have a directed edge list that records who followed whom. A mutual “friendship” exists only if both directions appear (A→B and B→A). Schema and sa...
Find least active countries
You are given an ads activity table. Table: ad_activity - ad_id BIGINT — unique ad identifier - advertiser_id BIGINT — advertiser that owns the ad - c...
Explain Bootstrap and Prove Uniformity
You are interviewing for a Data Scientist role. Answer the following statistics-theory prompts: 1. What is the bootstrap, when would you use it, and c...
How to deploy and tune multimodal models?
Question You are interviewing for a new-grad machine learning / data scientist role at ByteDance. Answer the following related machine-learning and LL...
Evaluate New Feed-Ranking Algorithm with A/B Testing
Experiment Design: New Feed-Ranking Algorithm and Daily Active Minutes Scenario A social-media platform plans to evaluate a new feed-ranking algorithm...
Walk through an A/B test end-to-end
Walk through how you would design, run, and analyze an A/B test for a product change. Your answer should include: - Hypothesis framing and choosing pr...
Match alphanumeric patterns in a stream
Given a reference 7–8 character alphanumeric code and four candidate codes, select the exact match as quickly as possible. Design a system that: - Eff...
Identify Key Drivers of Delivery Decline in Los Angeles
Scenario DoorDash sees a 10% drop in the number of completed deliveries in Los Angeles week-over-week. Question How would you identify, attribute, and...
Clean scores and return top 5 students
Implement a Python function to clean and rank student scores. You are given a table (or DataFrame) students with schema: | column | type | notes | |--...
How do you split coins to match heads?
There are N coins on a table. You are told that exactly H of them are heads-up (you do not know which ones). You must split the coins into two piles s...
Answer four core statistics questions
Problem set (timed) Answer the following four questions. 1) Covariance of order statistics Let \(X\) and \(Y\) be independent \(\mathrm{Unif}(0,1)\). ...
Design a house-price prediction model
Problem You are asked to build a model to predict house sale prices for a city of your choice. Data (assume typical real-estate fields) You have a his...
Calculate CTR and ad revenue
This interview included two SQL tasks. Task 1: Compare CTR during peak and non-peak hours You are given three tables: - ads(ad_id BIGINT, advertiser_i...
Resolve Simpson’s paradox in email A/B test
Email campaign experiment with Simpson’s paradox A marketing team tests a new email variant B vs control A. The experiment ran for two weeks in two ci...
Sketch distributions and compare mean/median/mode
Sketching distributions and comparing mean, median, and mode This is a conceptual statistics question with two independent scenarios. For each, you sk...