Jane Street Data Scientist Interview Questions
Practice the exact questions companies are asking right now.
"I got asked a hardcore MCM DP question and I saw it on PracHub as well. Solved that question in 5 minutes. Without PracHub I doubt I could solve it in 5 hours. Though somehow didn't get hired, perhaps I guess I solved it too fast? /s"
"Believe me i'm a student here jn US. Recently interviewed for MSFT. They asked me exact question from PracHub. I saw it the night before and ignored it cause why waste time on random sites. I legit wanna go back and redo this whole thing if I had chance. Not saying will work for everyone but there is certainly some merit to that website. And i'm gonna use it in future prep from now on like lc tagged"
"10 years of experience but never worked at a top company. PracHub's senior-level questions helped me break into FAANG at 35. Age is just a number."
"I was skeptical about the 'real questions' claim, so I put it to the test. I searched for the exact question I got grilled on at my last Meta onsite... and it was right there. Word for word."
"Got a Google recruiter call on Monday, interview on Friday. Crammed PracHub for 4 days. Passed every round. This platform is a miracle worker."
"I've used LC, Glassdoor, and random Discords. Nothing comes close to the accuracy here. The questions are actually current — that's what got me. Felt like I had a cheat sheet during the interview."
"The solution quality is insane. It covers approach, edge cases, time complexity, follow-ups. Nothing else comes close."
"Legit the only resource you need. TC went from 180k -> 350k. Just memorize the top 50 for your target company and you're golden."
"PracHub Premium for one month cost me the price of two coffees a week. It landed me a $280K+ starting offer."
"Literally just signed a $600k offer. I only had 2 weeks to prep, so I focused entirely on the company-tagged lists here. If you're targeting L5+, don't overthink it."
"Coaches and bootcamp prep courses cost around $200-300 but PracHub Premium is actually less than a Netflix subscription. And it landed me a $178K offer."
"I honestly don't know how you guys gather so many real interview questions. It's almost scary. I walked into my Amazon loop and recognized 3 out of 4 problems from your database."
"Discovered PracHub 10 days before my interview. By day 5, I stopped being nervous. By interview day, I was actually excited to show what I knew."
"I recently cleared Uber interviews (strong hire in the design round) and all the questions were present in prachub."
"The search is what sold me. I typed in a really niche DP problem I got asked last year and it actually came up, full breakdown and everything. These guys are clearly updating it constantly."
Solve probability and game-theory puzzles
You are interviewing for a quant trading internship. Work through the following probability and game-theory puzzles. There is no need to answer instan...
Design a Real-vs-Fake DNA Classifier
Question You are given DNA sequences over the alphabet {A, C, G, T}, where sequence lengths may vary. You have: - a small labeled dataset containing b...
Alternating Die-Roll Game: Optimal Accept/Reject Strategy
Two players, A and B, play the following game with a fair 21-sided die whose faces are labeled with the integers $-10, -9, \ldots, 9, 10$ (one integer...
Four Fair Coins: Expected Payoff and Pricing Two Magic Wands
You play the following game: four fair coins are tossed at the same time. For every coin that lands heads, you are paid \$1. The interviewer walks you...
Sealed-Bid Auction for a Box of 200 Coin Flips (and an Informed Opponent)
You are one of two bidders in a sealed-bid auction for a box. The box's payout is determined by flipping 200 fair coins: it pays \$1 for every coin th...
Bounds on the Probability of Rain on at Least One Weekend Day
The probability that it rains on Saturday is $p$, and the probability that it rains on Sunday is $q$. Nothing is said about whether the two days are i...
Analyze trading RFQ competitiveness data
This question evaluates a candidate's skills in exploratory data analysis, Excel-based feature engineering, basic statistical modeling, and interpreta...
Which Dice Game Wins More Often: One Six in 4 Rolls, or Double Sixes in 24 Rolls?
You are offered two dice games and asked to decide which one gives you a better chance of winning. - Game 1: Roll one fair six-sided die 4 times. You ...
Five Pumpkins Weighed in Every Pair: Find the Total Weight
You have 5 pumpkins. You weigh them two at a time, in every possible pairing, and the scale readings for the ten pairs are: $$21,\ 22,\ 23,\ 24,\ 25,\...
Pick a Number 1-100 Where the Higher Pick Pays a 10-Point Penalty: Optimal Strategy
Two players simultaneously each pick an integer from 1 to 100 (inclusive). The winner is decided as follows: take the larger of the two picks, subtrac...
Coin-Flip Race to Four: Game Length and a Conditional Win Probability
Two players play a coin-flipping game with a single fair coin. The coin is flipped once per round. Every heads counts for Player 1, and every tails co...
Dice Duel: 30-Sided Die vs. 20-Sided Die with One Blind Reroll
Alice and Bob play a dice game. Alice has a fair 30-sided die (faces $1$ through $30$) and Bob has a fair 20-sided die (faces $1$ through $20$). Each ...
Minimum Common Pairwise Correlation Among Seven Identically Distributed Random Variables
Suppose $X_1, X_2, \ldots, X_7$ are seven random variables defined on the same probability space. Each has mean $0$ and variance $1$, and they are ide...
Pricing a Mystery Money Box: Expected Value, Adverse Selection, and Competition
A company manufactures sealed boxes. Each box contains a cash amount that is an integer number of dollars drawn uniformly at random from $1$ to $100$ ...
Solve queue switch and coin change puzzles
This entry contains two separate interview-style quantitative/algorithmic questions. --- 1. Queue switching decision problem You are standing in a sin...
Quant Probability Brainteasers: Pizza Bounds, Coin Scores, Ant on a Cube, Shoelace Loops, and Paint Mixing
You are in a quantitative research interview. The interviewer works through a series of short probability puzzles and expects you to reason out loud, ...
Optimal Stopping for Die Rolls That Bust on Perfect Squares
You repeatedly roll a fair six-sided die and keep a running cumulative sum $S$ of all the values rolled so far (starting from $S = 0$ before the first...
Two Opaque Boxes: Place or Take for Maximum Expected Payoff
You are playing a one-player game with two opaque boxes, both of which start empty. The game lasts exactly 100 turns, and on every turn you must choos...
Streaming Equivalence of Two Trade Feeds with Per-Company Ordering
A market-data system receives trade events from two independent feeds. Each event is a pair (company, trade_id) identifying one trade for one company....