Interview puzzles
Quant puzzles ← Back Classic brainteasers from quant and trading interviews. Try each one first, use the hints if you are stuck, then watch the animated solution step by step.
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All topics Probability Expected value and Markov Counting and geometry Logic Games and betting
1 Russian roulette: spin again? easy Probability 2 One die, one reroll easy Games and betting 3 Burning ropes: measure 45 minutes easy Logic 4 Meeting at the cafe easy Counting and geometry 5 1,000 bottles of wine easy Logic 6 Monty Fall: the clumsy host easy Games and betting 7 The Returning Explorer easy Logic 8 Which Switch? easy Logic 9 Lucky Candy easy Probability 10 All Girls World? easy Probability 11 Tigers and the Sheep easy Games and betting 12 Duck and the Fox easy Games and betting 13 The Plane in the Wind easy Logic 14 Pair of Socks easy Counting and geometry 15 Half Time: Road Accidents easy Probability 16 Monty Hall: The Three Doors easy Probability 17 Prisoners in a Line: Colored Hats easy Logic 18 Knight and Knave at the fork easy Logic 19 Water and wine mixture easy Logic 20 100 light bulbs toggle easy Counting and geometry 21 Fair coin from biased coin easy Probability 22 Subway train schedule easy Probability 23 Two eggs and 100 floors easy Counting and geometry 24 e^pi or pi^e easy Logic 25 Shooting in circle easy Games and betting 26 Invisible dice easy Probability 27 Dark room card flip easy Logic 28 Cheating husbands easy Logic 29 Father of Lies easy Probability 30 Devil's Penny easy Games and betting 31 The lost boarding pass medium Probability 32 One extra coin medium Probability 33 Stick to triangle medium Counting and geometry 34 Sum to exceed one medium Expected value and Markov 35 Double-headed coin medium Probability 36 100 coins in a line medium Games and betting 37 Pirates and the gold medium Logic 38 Card color prediction medium Probability 39 Ant on a cube medium Expected value and Markov 40 Rabbit on the Staircase medium Counting and geometry 41 Sharing Wood medium Logic 42 Infinity and Beyond medium Logic 43 Chuck a Luck medium Probability 44 Multilingual Group medium Counting and geometry 45 Guess the Toss medium Games and betting 46 Pattern on Snowflakes medium Expected value and Markov 47 King's Salary medium Games and betting 48 Counting on Friends medium Counting and geometry 49 Random Ratio medium Probability 50 Innocent Monkey medium Expected value and Markov 51 Consecutive Heads medium Expected value and Markov 52 Chess Tournament medium Probability 53 Number of Double Heads medium Probability 54 Breaking Stick medium Probability 55 Prisoners in a Line: Ten Colors medium Logic 56 Rainbow Hats medium Logic 57 Two Equations and Three Unknowns medium Logic 58 Domino Covering medium Counting and geometry 59 Fruit Magic medium Counting and geometry 60 Catching Ants medium Counting and geometry 61 Color Complex: Monochromatic Rectangle medium Counting and geometry 62 Light Bulbs in a Ring medium Logic 63 Chocolate Bar Breaks medium Counting and geometry 64 Dead Men Walking: Zombie Collisions medium Counting and geometry 65 Square Infection on a Grid medium Counting and geometry 66 To Begin or Not to Begin? medium Games and betting 67 Crazy Postman medium Probability 68 Single Bid medium Probability 69 Waiting for a Truck medium Probability 70 The Blind Archer medium Probability 71 Min and Max medium Logic 72 Crazy Clock medium Logic 73 Scaling a Square medium Logic 74 Weird Sequences medium Counting and geometry 75 Color Switches medium Probability 76 The Tuesday boy hard Probability 77 Hopping frog on lily pads hard Expected value and Markov 78 Four points on a sphere hard Counting and geometry 79 100 prisoners and the light bulb hard Logic 80 Random walk on a circle hard Expected value and Markov 81 Colored Runs of Cards hard Expected value and Markov 82 Distance from North Pole hard Probability 83 Expected Breakup Length hard Probability 84 Messing with Envelopes hard Probability 85 The Noodles hard Expected value and Markov 86 Distinct Number Draws hard Probability 87 Greed for an Ace hard Expected value and Markov 88 Random Point on a Disk hard Probability 89 Enclosing the Center hard Probability 90 Random Walk: First Exit hard Expected value and Markov 91 Left Some Candies hard Probability 92 Catching the Submarine hard Games and betting 93 Catching the Spy hard Logic 94 Game of Divisors hard Games and betting 95 Counter Strike hard Logic 96 Sharing a Secret hard Counting and geometry 97 Weights Reckoning hard Logic 98 Gas Stations on Circular Trek hard Logic 99 Bricking Box hard Counting and geometry 100 Clan Size hard Probability 101 Prisoner Hats at Infinity hard Logic 102 Consecutive Sums hard Counting and geometry 103 Intersecting Pillars hard Counting and geometry