DRW Probability & Brain-Teasers Interview

The DRW Probability & Brain-Teasers interview is stage 3 of 6 in the DRW interview process, after the Recruiter / Phone Screen. Format: 45-60 min - video. Probability, expectation, and brain-teasers with follow-ups -- the core quant screen.

What the Probability & Brain-Teasers tests

Streaks, gambler's ruin, waiting times, and order statistics are common.

QuantVault maps 64 practice problems to this round. By topic, the biggest groups are expectation (28), probability (22), combinatorics (6), brain teasers (5); by difficulty, 25 easy, 35 medium and 4 hard. 14 of them were reported by candidates who interviewed at DRW, most recently in Sep 2026.

• Probability and statistics are covered in the single 45-minute Zoom interview before the final.

How to prepare for the Probability & Brain-Teasers

• Estimate first, then formalize.
• Waiting-time and streak problems -- know expected flips to a pattern and streak independence.
• Expect follow-ups extending the result.

Further reading: How quant superdays work · Behavioral questions at trading firms · Market-making game interview guide.

Question types in this round

The 5 largest question types in the DRW Probability & Brain-Teasers practice set; across them the most common sub-topics are expected value, conditional probability, discrete probability, symmetry, independence, first-passage and stopping times. The questions themselves, with worked solutions, are in the round practice.

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