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.
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"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."
Match readings with latest same-city humidity
Problem You are given two time-sorted lists of sensor readings: - Temperature records: (time, city, reading) - Humidity records: (time, city, reading)...
Solve Market-Risk and Probability Questions
Question Answer the following quantitative interview questions for a market-risk / data-scientist screen at Morgan Stanley. 1. Stress testing WTI and ...
Evaluate piecewise linear function at x
You are given a polyline defined by n 2D points \((x_i, y_i)\). Connecting consecutive points with straight line segments forms a piecewise linear fun...
Assess Group Video Chat Demand
You are a Data Scientist supporting a social communication product. The company is considering launching a Group Video Chat feature, but the feature d...
Estimate total attendance from size-biased reservation sample
You run a restaurant with N = 10,000 reservations in a day. Each reservation j has: - Reserved party size: \(R_j\) (positive integer) - Actual number ...
Clean and Merge Housing Data
You are given two pandas DataFrames from a house-price screening exercise. house_sales_raw - listing_id INT - sale_price FLOAT, nullable in rows reser...
Compute Optimal Die Re-roll Strategy
A fair six-sided die pays its face value in dollars. You may roll up to three times total. - After the first or second roll, you may either keep the o...
How do you resolve partner conflict?
Describe a time you worked with cross-functional partners such as Product, Engineering, Design, Marketing, or another business team on an important pr...
Implement palindrome check and valid parentheses
You have 20–25 minutes per problem. Implement the following two functions and be prepared to explain your approach and time/space complexity. Problem ...
Explain KNN and PCA and key tradeoffs
In a Data Scientist internship interview, you are asked ML fundamentals: 1) K-Nearest Neighbors (KNN) - Explain how KNN works for classification and r...
Model Driver Acceptance Probability
Design a machine learning system to predict the probability that a driver accepts a trip or delivery offer. Your answer should cover: - the prediction...
Design an Unbiased Upgrade Experiment
The Google app releases a new Android version. Every Android user sees a pop-up encouraging installation, but installation is voluntary: some users up...
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: -...
Estimate constant under absolute loss
Suppose you have observed target values \(y_1, y_2, \dots, y_n\), and you want to fit the simplest possible model that predicts the same constant valu...
Find minimum swaps to sort array with duplicates
Problem Given an integer array nums of length n that may contain duplicate values, you may perform swaps where you choose any two indices i and j and ...
Should you play a dice payout game?
Two players each roll a fair six-sided die once. - If you win (your roll > opponent’s roll), the opponent pays you $n. - If the opponent wins or it’s ...
Write SQL for top drivers and cancellation rates
Question You work on a rideshare / ride-hailing product that connects drivers and riders, with a focus on airport pickups. Using SQL, answer the quest...
How do you sample uniformly from an infinite stream?
Coding (Python) — Random sampling from an infinite stream You receive an unbounded/infinite stream of items (e.g., numbers or events). You cannot stor...
Plan parking demand for a retail store
A retailer similar to Best Buy is considering building a customer parking lot next to one of its stores. You are asked to determine what data you woul...
Answer Product DS HR Screen
You are preparing for a 30-minute HR screening interview for a Product Data Scientist role at Shopify. Prepare strong, structured answers to the follo...