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Solve complete questions with progressive hints, worked solutions and Python implementations. Each question explains its assumptions and source match. Original interpretations are labelled explicitly.

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Public standard problems and original exercises; hidden Trading Interview questions have not been verified.

174 titles have been investigated but remain unresolved. Their missing details are recorded without adding substitute exercises. Every playable question has a guided animated answer; selected questions also have custom diagrams.

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752 matching entries · page 1 of 16

Probability and Statistics · Easy

Liver Disease

Original interpretation · Match confidence: medium

Jane Street · Topic guidanceSusquehanna (SIG) · Topic guidance
About this question’s source match

The title and category identify this topic, but do not reveal the private statement. The explicitly specified scenario is an original, title-specific interpretation. Exact Trading Interview wording, numbers and requested subparts remain unverified; this is not claimed to be the hidden source question.

For a fictional disease population, prevalence is 2%. A test is positive for 90% of affected people and 5% of unaffected people. Find the chance an individual has the disease given a positive test, and given a negative test.

Assumptions and constraints

  • Hypothetical fixed rates; one random person and one test.
  • Give exact expressions where possible and justify each requested result.

Examples

10000 people expected counts
→ 180 true positive,490 false positive

Only 180 of 670 expected positives are affected.

Company preparation relevance

These links connect this exercise to companies’ public examples or stated interview topics. They do not establish that a company asked this exact Learnr question.

  • Jane Street

    Official topic guidance

    Topic overlap: conditioning in “Given a Seven” (known dice sum),“Liver Disease” (test result),“Which Die Was It” (die identity). The page recommends early clubs/diamonds for interview preparation and identifies conditional probability among their topics.

    Probability Playing Cards — official preparation guidance ↗
    Evidence scope and uncertainty

    Preparation-topic recommendation only. No individual deck card is identified as a match. The page explicitly distinguishes harder cards as recreational. It does not say every card is interview preparation.

    These are Learnr-authored exercises selected for topic overlap. The company does not name these catalogue titles or verify that these exact questions were asked.

  • Susquehanna (SIG)

    Official topic guidance

    Topic overlap: payoff decisions “Cash or Reroll”, stake-growth reasoning “Kelly Betting #1” and conditional probability “Liver Disease” practice probability, odds, expectancy and decision-making under uncertainty discussed on the firm’s trading-careers page.

    Susquehanna — Trading careers ↗
    Evidence scope and uncertainty

    Trading education and candidate puzzle culture. This page supports preparation relevance, not exact interview-question provenance.

    These are Learnr-authored exercises selected for topic overlap. The company does not name these catalogue titles or verify that these exact questions were asked.

References

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Catalogue metadata captured 2026-10-12. Metadata source.