Data Scientist ML System Design Interview Questions

Practice 13 real ML System Design interview questions for Data Scientist roles. From companies including Citadel, PayPal, Two Sigma, Microsoft, Millennium.

13 Questions 9 Companies07.30.2026
Showing 13 results
Role
Millennium logo
Millennium
Medium
Data Scientist

Design a Governed Agent for Portfolio Rebalancing

Design a Governed Agent for Portfolio Rebalancing Design an agentic architecture that can propose and, when authorized, execute portfolio rebalancing....

ML System Design
2
0
19 people solved
Jul 30, 2026
Capital One logo
Capital One
Medium
Data ScientistSenior+ Locked

Explain an ML Project from Model Development Through Deployment

Prepare a data science project walkthrough that connects the prediction target and validation design to an operational decision. Explain model selecti...

ML System Design
4
0
40 people solved
May 31, 2026
Uber logo
Uber
Medium
Data ScientistNew Grad Locked

Design Uber Eats Restaurant Recommendations

This question evaluates a candidate's ability in end-to-end machine learning system design for personalized restaurant recommendations in a food-deliv...

ML System Design
27
0
218 people solved
Apr 30, 2026
Tower logo
Tower
Hard
Data Scientist

Debug Oscillating GPU Utilization During Training

A distributed neural-network training job shows GPU utilization repeatedly swinging from about 90% down to 20%. Explain how you would diagnose the thr...

ML System Design
0
0
2 people solved
Jul 26, 2026
Microsoft logo
Microsoft
Medium
Data Scientist

Design Product-Description Content Moderation at Marketplace Scale

Prompt Design a system that detects and handles inappropriate text in seller-uploaded product descriptions for a marketplace containing billions of pr...

ML System Design
4
0
42 people solved
May 4, 2026
Two Sigma logo
Two Sigma
Hard
Data Scientist

Predict Citi Bike Demand at a Specific NYC Station

Citi Bike is New York City's bike-share system: riders pick up a bike at one docked station and drop it off at another. Operations needs to know how m...

ML System Design
9
1
74 people solved
Nov 28, 2025
Two Sigma logo
Two Sigma
Hard
Data Scientist

Predicting Stock Prices from Twitter Data

Predicting Stock Prices from Twitter Data Suppose you have access to a large stream of Twitter data — tweets with their text, timestamps, and author m...

ML System Design
5
0
34 people solved
Dec 2, 2025
Virtu logo
Virtu
Medium
Data Scientist

Design Basketball Shot Outcome Prediction

Design a machine learning system that predicts whether a basketball shot will be made or missed using only information available at the moment the pla...

ML System Design
4
0
40 people solved
Jan 22, 2026
Citadel logo
Citadel
Medium
Data Scientist Locked

Stabilize LLM inference and estimate needed repeats

This question evaluates skills in designing reliable LLM inference pipelines and in statistical modeling of stochastic outputs, including reproducibil...

ML System Design
5
0
86 people solved
Oct 9, 2025
PayPal logo
PayPal
Hard
Data Scientist

Detect credit-card transaction fraud

Credit-Card Fraud Detection: Real-Time Decisioning and System Design You are designing a real-time decisioning system for card-payment authorizations ...

ML System Design
16
0
176 people solved
Aug 4, 2025
Citadel logo
Citadel
Hard
Data Scientist

Design a time-series home-buy decision classifier

Take‑Home: Classifying Buy‑Now vs Wait Decisions in Housing Time Series Context You are given a monthly panel of regional housing and macro time serie...

ML System Design
9
0
79 people solved
Aug 13, 2025
Citadel logo
Citadel
Hard
Data Scientist

Build a regression model for wind power output

Task: Snapshot Regression for Turbine-Level Power Prediction (Non–Time-Series) You are given turbine-level SCADA snapshots and concurrent weather data...

ML System Design
7
0
74 people solved
Aug 13, 2025
PayPal logo
PayPal
Hard
Data Scientist

Design fraud detection from raw transactions

Design fraud detection from raw transactions System Design: End-to-End Transaction Fraud Detection Context You are given a large, multi-table dataset ...

ML System Design
8
0
91 people solved
Jul 31, 2025

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