Probability Interview Questions
Probability is the backbone of quant interviews — from basic counting and independence to conditional reasoning. These questions build the intuition trading and research interviews assume.
120 probability questions · 43 free to practise now.
- 1 before 2EasyProbabilityCombinatoricsView →
- All-distinct PINEasyProbabilityCombinatoricsView →
- Ants on a triangleEasyProbabilityBrainteasersView →
- Asking around for a birthday matchEasyProbabilityExpected ValueView →
- At least one 3EasyProbabilityView →
- Drawing a pairEasyProbabilityCombinatoricsView →
- Even productEasyProbabilityView →
- Even sum from two diceEasyProbabilityView →
- Even-size subsetEasyProbabilityCombinatoricsView →
- Exactly five headsEasyProbabilityCombinatoricsView →
- Expected flips to first headEasyProbabilityExpected ValueView →
- Face card given a heartEasyProbabilityConditional Probability & ExpectationView →
- Fair price of a heads payoutEasyProbabilityExpected ValueView →
- First ace before first kingEasyProbabilityCombinatoricsView →
- Gambler's fallacy checkEasyProbabilityConditional Probability & ExpectationView →
- Hopping rabbitEasyProbabilityCombinatoricsView →
- Inside the inner circleEasyProbabilityView →
- Lottery drawEasyProbabilityCombinatoricsView →
- Make a market on a coin's heads countEasyProbabilityExpected ValueView →
- Matching a specific birthdayEasyProbabilityView →
- Maximum of three uniformsEasyProbabilityRandom VariablesView →
- No Poisson arrival in a windowEasyProbabilityStochastic ProcessesView →
- Probability of hitting an exact valueEasyProbabilityRandom VariablesView →
- Probability two dice sum to 7EasyProbabilityCombinatoricsView →
- Red or kingEasyProbabilityView →
- Rolls to see a 6EasyProbabilityExpected ValueView →
- Second card redEasyProbabilityConditional Probability & ExpectationView →
- Shared-birthday pairsEasyProbabilityExpected ValueView →
- Stop at the first girlEasyProbabilityView →
- Sum of seven given a known dieEasyProbabilityConditional Probability & ExpectationView →
- The memoryless propertyEasyProbabilityRandom VariablesView →
- Three dice, increasingEasyProbabilityCombinatoricsView →
- Two coins, at least one headEasyProbabilityConditional Probability & ExpectationView →
- Who wins the first head?EasyProbabilityView →
- A 5 before a 7MediumProbabilityView →
- First consecutive repeatMediumProbabilityExpected ValueView →
- First head on an even flipMediumProbabilityView →
- Monty HallMediumProbabilityConditional Probability & ExpectationView →
- Tennis: two sets or three?MediumProbabilityView →
- The birthday problemMediumProbabilityCombinatoricsView →
- Two aces drawnMediumProbabilityCombinatoricsView →
- Two childrenMediumProbabilityConditional Probability & ExpectationView →
- de Méré's betMediumProbabilityMarket Making & Betting GamesView →
- Absorption probability on a lineMediumProbabilityStochastic Processes Premium
- An ace in every pileMediumProbabilityCombinatorics Premium
- At least two sixes in five rollsMediumProbabilityRandom Variables Premium
- Attributing a superposed Poisson eventMediumProbabilityStochastic Processes Premium
- Bertrand's boxMediumProbabilityConditional Probability & Expectation Premium
- Counting flushesMediumProbabilityCombinatorics Premium
- Counting straightsMediumProbabilityCombinatorics Premium
- Density of a sum of two uniformsMediumProbabilityRandom Variables Premium
- Distinct birthdays representedMediumProbabilityExpected Value Premium
- Edge from a biased coinMediumProbabilityExpected Value Premium
- Fair outcome from a biased coinMediumProbabilityStatistics Premium
- Fair price of a three-flip heads gameMediumProbabilityExpected Value Premium
- Fourth moment of a normalMediumProbabilityRandom Variables Premium
- Full housesMediumProbabilityCombinatorics Premium
- Gambler's ruin (unfair)MediumProbabilityStochastic Processes Premium
- HT before HH in coin flipsMediumProbabilityStochastic Processes Premium
- House edge in rouletteMediumProbabilityExpected Value Premium
- Joint default rangeMediumProbabilityFinance & Derivatives Premium
- Large sum given a sixMediumProbabilityConditional Probability & Expectation Premium
- Letters into envelopesMediumProbabilityExpected Value Premium
- Minimum of three uniformsMediumProbabilityRandom Variables Premium
- Minimum of two exponentialsMediumProbabilityRandom Variables Premium
- Monty Hall with 100 doorsMediumProbabilityConditional Probability & Expectation Premium
- No two heads in a rowMediumProbabilityCombinatorics Premium
- Parlay combined oddsMediumProbabilityMarket Making & Betting Games Premium
- Points on a semicircleMediumProbability Premium
- Poisson inter-arrivalsMediumProbabilityStochastic Processes Premium
- Pricing a digital die betMediumProbabilityExpected Value Premium
- Prime sumMediumProbability Premium
- Rare-event Poisson approximationMediumProbabilityRandom Variables Premium
- Russian roulette, re-spunMediumProbabilityConditional Probability & Expectation Premium
- Second-price auction strategyMediumProbabilityMarket Making & Betting Games Premium
- Simulate probability pMediumProbabilityProgramming & DSA Premium
- Spam filterMediumProbabilityConditional Probability & Expectation Premium
- Stationary distribution of a two-state chainMediumProbabilityStochastic Processes Premium
- Sum of 10 with three diceMediumProbabilityCombinatorics Premium
- Sum of independent PoissonsMediumProbabilityRandom Variables Premium
- The cab problemMediumProbabilityConditional Probability & Expectation Premium
- The larger die shows a 4MediumProbabilityRandom Variables Premium
- The two-headed coinMediumProbabilityConditional Probability & Expectation Premium
- Thinning a Poisson processMediumProbabilityStochastic Processes Premium
- Three distinct diceMediumProbabilityCombinatorics Premium
- Three dots on a squareMediumProbabilityCombinatorics Premium
- Three prisonersMediumProbabilityConditional Probability & Expectation Premium
- Two reds in a row from a shrinking urnMediumProbabilityConditional Probability & Expectation Premium
- Two uniforms summing past 1.5MediumProbabilityCalculus Premium
- Variance-minimizing hedgeMediumProbabilityStatistics Premium
- Which coin produced two heads?MediumProbabilityConditional Probability & Expectation Premium
- Which deck for two reds?MediumProbability Premium
- Will they meet?MediumProbability Premium
- Within distance d on the unit intervalMediumProbabilityCalculus Premium
- A 12 before two 7sHardProbabilityStochastic Processes Premium
- A void suit in bridgeHardProbabilityCombinatorics Premium
- Amoeba extinctionHardProbabilityStochastic Processes Premium
- Bertrand's chordHardProbabilityBrainteasers Premium
- Best-of-seven underdogHardProbabilityRandom Variables Premium
- Bluffing frequency in pokerHardProbabilityExpected Value Premium
- Branching process extinction (critical)HardProbabilityStochastic Processes Premium
- Branching process extinction (supercritical)HardProbabilityStochastic Processes Premium
- Broken-stick triangleHardProbability Premium
- Buffon's needleHardProbabilityCalculus Premium
- Connecting noodlesHardProbabilityExpected Value Premium
- Correlation of min and maxHardProbabilityRandom Variables Premium
- Ehrenfest urn stationary distributionHardProbabilityStochastic Processes Premium
- Exactly one pairHardProbabilityCombinatorics Premium
- First-price auction shadingHardProbabilityExpected Value Premium
- Gambler's ruinHardProbabilityStochastic Processes Premium
- Laplace's rule of successionHardProbabilityConditional Probability & Expectation Premium
- Prisoners and the boxesHardProbabilityBrainteasers Premium
- Reflection principle for the maximumHardProbabilityStochastic Processes Premium
- The all-pay auctionHardProbabilityExpected Value Premium
- The boy born on a TuesdayHardProbabilityConditional Probability & Expectation Premium
- The drunk passengerHardProbabilityConditional Probability & Expectation Premium
- The two-envelopes paradoxHardProbabilityConditional Probability & Expectation Premium
- Triangle from three independent sticksHardProbabilityCalculus Premium
- Triangle that swallows the centerHardProbabilityBrainteasers Premium
- Two positive testsHardProbabilityConditional Probability & Expectation Premium
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