10 Servants Find Max Wine Kegs

Finding poisoned wine keg with 10 testers is a medium quant interview question on Brain Teasers, reported to have been seen at Goldman Sachs, Jane Street, Old mission and Two Sigma.

Difficulty Medium Topic Brain Teasers Reported at Goldman Sachs, Jane Street, Old mission, Two Sigma

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This classic brain teaser is about using a limited number of binary outcomes to distinguish among many possibilities. Instead of simple trial and error, it forces you to think in terms of information content and how to encode many different scenarios with a small set of yes/no signals. It looks like a puzzle about wine and poison, but it is really a question about efficient information design under strict constraints.

This kind of quant prep trains you to see testing as information encoding, to work comfortably with exponential growth, and to map real-world setups into abstract binary structures. It sharpens your ability to translate a story problem into a clean combinatorial or information-theoretic model, a key habit in high-level quant interviews.

In quant interviews, this matters because it probes more than calculation: it checks whether you naturally think in bits, codes, and capacity. Top quant interviews often reward candidates who can recognize hidden information-structure quickly, reason about limits, and justify scaling laws clearly. This is the same mindset used in designing experiments, factor models, and smart backtests in quantitative finance.

What it tests

This class of problems is governed by the principle of information encoding: when each test yields a binary outcome (such as alive/dead), the maximum number of distinct cases you can distinguish is determined by the number of unique binary strings you can form with your testing agents. With $k$ independent binary outcomes, you can uniquely identify $2^k$ possibilities, because each outcome sequence corresponds to a unique identifier. This is fundamentally a question about the capacity of a binary code to label objects, and it arises in contexts like error detection, group testing, and combinatorial identification. The reason this works is that each agent (or test) acts as a bit in a binary number, and the full set of outcomes forms a complete basis for the space of possible cases. The limitation is not the number of objects or tests, but the number of unique patterns you can observe, which grows exponentially with the number of binary tests.

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