All topics
Probability Interview Questions
Probability is the backbone of every quant interview: conditional probability, Bayes’ theorem, expected value and classic puzzles like Monty Hall and the two-children problem. All 25 probability questions below come with a full worked solution — sign in to check your answers and track your progress.
Read the guide: Probability Interview Questions for Quant Roles (With Answers)
2153%Easy2256%Easy2341%Medium2452%Medium2569%Easy2655%Medium2785%Easy2855%Medium2943%Medium3063%Medium3172%Medium3266%Easy3341%Medium3462%Medium3571%Medium3669%Medium3752%Medium3879%Easy3960%Easy4051%Medium4144%Hard4245%Hard4352%Medium4444%Medium4558%Medium
Coin Toss — Two Heads
Jane Street
Monty Hall
Goldman SachsMorgan Stanley
Roll Until All Six Faces
GoogleTwo Sigma
Birthday Problem
Goldman SachsCitadel
Flips Until First Head
OptiverIMC Trading
Drunk Passenger
Jane StreetCitadel
Two Dice Sum to 7
OptiverIMC Trading
Bayes — Disease Test
Goldman SachsTwo Sigma
Broken Stick Triangle
Jane StreetCitadel
Top Two Aces
SIG / SusquehannaOptiver
Hat Check
Jane StreetDE Shaw
Two Children
Goldman SachsMorgan Stanley
Expected Max of Two Dice
OptiverIMC Trading
Russian Roulette — Spin?
Jane StreetCitadel
Expected Min of Two Dice
OptiverSIG / Susquehanna
Poisson — No Arrivals
Two SigmaJump Trading
Exponential Survival
DE ShawMorgan Stanley
Expected Rolls for a Six
OptiverIMC Trading
At Least One Six
SIG / SusquehannaOptiver
Expected Max of Two Uniforms
Jane StreetCitadel
The Tuesday Boy
Jane StreetSIG / Susquehanna
The 100 Prisoners Problem
Jane StreetTwo Sigma
The Shorter Piece
OptiverMorgan Stanley
The Secretary Problem
Jane StreetDE Shaw
Galileo’s Three Dice
OptiverIMC Trading
Browse more topics, by firm, or see all problems.