Top 38
Prep plan
Updated weekly · Last refresh Aug 30

Duolingo Data Scientist Interview Questions

The questions to prepare for a Duolingo Data Scientist interview. Questions from real interview reports rank first. Updated weekly.

38questions
~5htotal time
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1
SQL & Data ManipulationStart here. 8 questions + 2 drills · ~87 min
2
A/B Testing & Experimentation3 questions · ~25 min
Design Test for New FeatureMedium

Design an A/B test for a new platform feature, including success metrics, power, guardrails, and a clear ship decision.

experiment designfeature evaluationA/B TestingDuolingo
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3
Metrics3 questions · ~25 min
Diagnose Conversion Drop Post LaunchMedium

Diagnose why conversion fell from 4.8% to 3.1% after a launch by breaking the metric across funnel steps, cohorts, and segments.

Funnel AnalysisConversion RateDiagnosisDuolingo
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4
Machine Learning5 questions · ~42 min
Predict Duolingo Churn RiskMedium

Tests churn modeling approach, feature/label construction, and evaluation for retention interventions.

Feature EngineeringRegularizationSupervised LearningDuolingo
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5
Statistics & Probability3 questions · ~25 min
Stats for Product TeamsMedium

Tests statistical communication skills and correct interpretation of experiment results.

Confidence IntervalsHypothesis TestingP-ValuesDuolingo
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6
Behavioral & Leadership11 questions · ~91 min
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7
More topics5 questions · ~42 min
ETL Pipeline With BackfillHard

Tests data engineering design for reliability, correctness, and operational handling of late events.

ETLBatch ProcessingOrchestrationDuolingo
User Focus and Educational ImpactEasy

Tests how you connect analytics and modeling decisions to user learning outcomes.

User ResearchUser NeedsProduct VisionDuolingo
Evaluate Learning Feature ImpactMedium

Tests causal thinking, metric tradeoff handling, and robust evaluation strategy for product changes.

PrecisionAccuracyRecallDuolingo
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The finish line: interview-readyComplete all 38 questions plus 2 hands-on drills to finish this plan.