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."
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"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."
Merge two sorted lists
Given two sorted lists (arrays) of integers A and B in non-decreasing order, merge them into a single sorted list. Requirements - Output must be sorte...
Design robber detection from surveillance video
You’re a Data Scientist on a team building a computer-vision system for public-safety monitoring. Problem Design an ML system that uses fixed surveill...
Describe your best team and your role
Question This is a two-part behavioral question. Answer both parts with concrete, specific examples (use STAR where relevant), and connect what you va...
Predict bike demand and avoid overfitting
You are given historical data for a city bike-sharing system. Available fields include station_id, hourly timestamp, number of bike pickups and return...
Find probability of overlapping blooms
Overlap Probability of Two Random Bloom Periods Assumptions - Time is measured in days over a 30-day horizon. - Each flower begins blooming once, at a...
Should Company Launch Vegan Burger Based on Profit Analysis?
Case: Launching a Vegan Burger — Unit Economics and Go/No-Go You are a data scientist supporting a product team that is deciding whether to launch a v...
Analyze Correlations and Generate Gaussians
You are interviewing for a quantitative data science role. Answer the following probability and simulation questions: 1. Let \(X\), \(Y\), and \(Z\) b...
Write SQL window functions for D7 retention
Assume you have the following tables (timestamps are in UTC). 1) game_sessions - user_id (STRING) - session_start_ts (TIMESTAMP) - country (STRING) Ea...
Analyze video flags and reviews with SQL
You are designing SQL queries for YouTube Trust & Safety. Use the schema and sample data below. Unless stated otherwise, treat a flag as reviewed if t...
Analyze shopping funnel with joins and windows
Write SQL (PostgreSQL) to analyze a 4-step shopping funnel: view_product → add_to_cart → checkout_start → purchase. Use the schema and sample data bel...
Compute CTR drop with exclusions
Assume today = 2025-09-01. Using ad delivery logs, find advertisers whose CTR in the last 7 days (2025-08-25 to 2025-08-31) dropped by at least 20% re...
Write SQL and Python for transaction analytics
You are given user and transaction data. Part A (SQL): Use a join and window functions to answer the prompts below using the following schema and samp...
Can bootstrap help reduce variance
An interviewer asks: “Can bootstrap help reduce variance?” Answer this question precisely. Distinguish between: 1) Using the bootstrap to estimate var...
How to Target Coupon Users
A ride-sharing company such as Lyft wants to launch a coupon campaign to increase commuter rides, but the coupon budget is limited. How would you anal...
Explain Feature, Model, and Validation Choices
You are interviewing for a Data Scientist role. Describe how you would approach an end-to-end machine learning project on large-scale data. In your an...
Find top advertisers and cost per KPI
You are given three advertising campaign tables. Table: campaign_spend | Column | Type | Description | |---|---:|---| | date | DATE | Calendar date in...
Estimate Revenues and Costs for New Amusement Park Launch
Amusement Park Case: Revenue, Costs, Profit, and Go/No-Go Context You are advising an amusement-park operator evaluating whether to build and launch a...
Maximize revenue from inventory sales
Problem A store has n different products. For each product i (0-indexed), you are given an integer quantity[i] representing how many units of that pro...
Explain SHAP in an ML System
Describe how you would build an end-to-end machine learning system for a business use case such as churn prediction, ad conversion prediction, or cont...
Evaluate ETA Impact on Conversion
You are a Senior Data Scientist at a ride-hailing company such as Uber. ETA refers to the estimated pickup time shown to a rider before they decide wh...