Interview practice
Jane Street-style probability & estimation practice
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Candidates consistently report probability and expected-value questions dominating the phone screens - mental math matters, but the reasoning is what's graded.
What this assessment looks like
Expected value and probability under time pressure: dice, cards and urn setups, ranking events by likelihood, and order-of-magnitude estimation questions with no clean closed form.
- Expected value computed fast and used to make a decision
- Conditional probability and Bayes updates without formal notation
- Ranking likelihoods rather than computing them exactly
- Fermi estimation: decomposing an impossible question into three easy ones
Train it here
- Likelihood Ranking - Order events from most to least likely - the exact screen-question format.
- Fermi Estimation - Piano tuners in Chicago, atoms in a body - scored on order of magnitude.
- Quitters Never Lose - A casino stopping-strategy game that is secretly a martingale lesson.
- Tail Risk - Rare events and fat tails - where naive expected value goes wrong.
Also reported at Jane Street
Market making · Stochastic processes · Quant developer coding
Hiring now: current Jane Street quant openings, refreshed daily.
Outcry is not affiliated with Jane Street and has no access to their assessment content. This page describes formats candidates publicly report, and the drills here train the underlying skills - they are not the firm’s questions.