Statistics & Math Interview Questions
Practice the exact questions companies are asking right now.
Compute probability an account is fake
A platform uses an automated classifier to flag potentially fake accounts. Assume: - Base rate: 2% of accounts are fake. - The classifier flags a fake...
Solve core probability and statistics questions
Answer the following short theory/computation questions (as in an OA multiple-choice section). Provide the key formula and a brief explanation. 1. Bay...
Explain and interpret p-values correctly
Context You are evaluating a change to a fraud decision rule (e.g., a new threshold or step-up authentication rule). You run an experiment comparing C...
Model wins-until-failure and expected future wins
You are given a DataFrame df where each row summarizes a player’s performance until their first loss. Input df columns: - player_id (string/int) - win...
Plan for timed probability assessment
Timed Probability/Statistics Assessment Strategy (30 Questions, Strict Time Limit) Prompt You are taking a timed online assessment with 30 probability...
Fake Accounts [AE]
Detecting and Managing Bad Accounts on a Social Platform 1) Probability of a Bad Account Sending Friend Requests Context: 1% of accounts are bad. Bad ...
Solve Markov, OLS-rotation, and coin-toss probability
Answer the following three interview questions. 1) Basic properties of a Markov (transition) matrix Let \(P\) be a transition matrix of a (time-homoge...
Compute probabilities and expectations in random processes
You are asked to solve the following probability/expectation questions. Unless stated otherwise, assume all random choices are uniform and independent...
Compute robust inference under skew and outliers
A/B test with skew, outliers, heteroskedasticity, missingness, and multiplicity You are comparing two independent product variants that produce a cont...
Compute decay, OLS, and classic probability results
You are asked several probability/statistics questions. 1) Radioactive decay (half-life) A radioactive atom has a half-life of 1 day. Assume each atom...
Solve probability and game-theory puzzles
You are interviewing for a quant trading internship. Answer the following probability / game-theory puzzles. 1) Two bottles, add/remove balls (100 rou...
Solve drunk-passenger probability and simulate outcome
Lost Boarding Pass Puzzle: Last Passenger's Seat Context: Technical screen for a Data Scientist (Statistics & Math). Setup - There are n passengers la...
Answer four core statistics questions
Problem set (timed) Answer the following four questions. 1) Covariance of order statistics Let \(X\) and \(Y\) be independent \(\mathrm{Unif}(0,1)\). ...
Estimate population singletons from a 10% log
A daily search log has one row per query string. You draw a 10% simple random sample of rows without replacement. Define a “unique query” (singleton) ...
Solve estimation and probability brainteasers
Answer the following independent brainteaser questions. State any assumptions you need. 1) Tile a floor: A floor is 15 ft × 20 ft. You will cover it w...
Diagnose and interpret regression assumptions
OLS for Signups with Diagnostics and Alternatives You are given a cleaned dataset with the following columns: - signups: non-negative integer count ta...
Explain confounding with an Uber example
Question In the context of analyzing Uber/Uber Eats data, explain what a confounding effect is. 1. Define confounder and why it can bias an observed r...
Explain Type I vs Type II errors
Prompt In hypothesis testing: 1. Define Type I error and Type II error. 2. Explain how they relate to significance level \(\alpha\) and power \(1-\bet...
Determine Probability of Shared Videos in Recommendations
Video Recommendation Probability and Product Trade-offs Scenario A video-recommendation system selects K distinct videos for each user from an invento...
Derive MLE and Bayesian posterior for Bernoulli
Bernoulli/Binomial Inference Task You observe n independent Bernoulli trials with unknown success probability p, and you record k successes (so K ~ Bi...