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."
Analyze EV, arbitrage, and bet sizing across games
Betting Games: EV, Variance, Arbitrage, and Sizing Context You will be shown payout tables or odds for three independent games. Your task is to quickl...
Compute Piecewise Linear Interpolation
You are given an unsorted list of distinct 2D points (x_i, y_i). When the points are sorted by x_i, connecting adjacent points forms a polyline. Given...
Compute the Probability for Two Uniform Variables
Let \(X\) and \(Y\) be independent random variables, each uniformly distributed on \([0,1]\). Define: - \(L = \max(X,Y)\) - \(S = \min(X,Y)\) What is ...
Write SQL for reply-based recipient metrics
You work on a social product and are given two tables. Assumptions (use these unless you state otherwise): - All timestamps are in UTC. - A “reply” is...
Discuss the future of quantitative finance
Outlook on Quantitative Finance (Next 5–10 Years) Context: You are interviewing for a data-focused role in quantitative finance. Provide a concise, st...
Find next terms in sequences
Pattern Recognition: Find the Rule and Next Term You are given 8 number sequences. For each sequence: - Identify a clear rule that generates the terms...
Implement two-pointer unique-pair sum search
Given a nondecreasing integer array nums and an integer target, return all unique value pairs [a, b] with a <= b such that a + b == target. Use the tw...
Handle imbalance, validate samples, and avoid overfitting
Answer the following applied ML questions. 1) Class imbalance You’re building a binary classifier where positives are rare. - What are practical ways ...
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...
Calculate Profit-Maximizing Price and Validate with Additional Data
Profit-Maximizing Price with Fixed/Variable Costs and a Price–Demand Curve Context You sell a single software product at one price P. You are given: -...
Determine Weekly Break-Even Point for Diaper Service
Diaper Service Unit Economics and Inventory Flow Scenario A weekly subscription diaper-delivery and cleaning service operates with these parameters: -...
Evaluate a Piecewise Linear Function
You are given an ordered list of 2D points [(x1, y1), (x2, y2), ..., (xn, yn)]. Connecting each consecutive pair of points forms a piecewise linear fu...
Write Queries for Pinterest Engagement Tasks
You are given several data-manipulation tasks based on Pinterest-style product data. Use UTC for all timestamp-to-date conversions unless stated other...
How do you test two variants vs control?
You ran an A/B/n experiment with 1 control and 2 treatment variants. The primary metric is conversion rate (each user either converts or not within th...
Show help, mistake recovery, and achievement
Behavioral & Leadership (Technical Screen) Answer all three parts below with concrete metrics, trade-offs, and decision rationale. Assume a Data Scien...
Implement robust word counts and min/max
You receive a 50GB UTF-8 text corpus on disk. Implement a Python solution that:\n- Streams the file without loading it fully into memory.\n- Counts ca...
Transform clickstream with pandas sessionization
Given a pandas DataFrame events with columns [user_id:int, ts:str ISO8601 or NaT, url:str, server_log_ts:datetime], build 30-minute inactivity session...
Identify country with highest sunny-day probability
Write SQL to find the country with the highest probability that a day is sunny. Use the schema and sample data below. Rules: consider a day sunny for ...
Explain and quantify bias-variance tradeoff
Bias–Variance Tradeoff: Intuition, Derivation, and Practical Tuning Task Explain the bias–variance tradeoff at two levels and connect it to model tuni...
Design a scalable video platform database
Design the relational database for a YouTube-like video company. Deliverables: 1) list the core tables with key columns, types, and constraints (users...