Statistics & Math Interview Questions
Practice 482 real Statistics & Math interview questions for 2026 — Statistics & Math interview questions gathered from actual interviews, with detailed solutions to guide your interview preparation. Covers companies like Meta, Capital One, Google, Amazon, and Optiver and roles such as Data Scientist, Quant/Trader, ML researcher, and Data Analyst. This collection is distinctive because problems range from applied inference
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Decide if a dice-betting game is favorable
You are considering a game against a “house” using fair six-sided dice. Rules: - You roll one die; the house rolls one die. - If your roll is strictly...
Diagnose and validate a ratio trend change
You are shown a weekly dispute_rate time series (disputes/succeeded_payments) that rises sharply, then partially reverts. Diagnose whether the change ...
Compare Normal vs Poisson; test dispersion and approximate tails
You collect n=200 independent minute-level event counts with sample mean x̄=14.5 and sample variance s²=16.2. 1) Under a Poisson(λ) model, derive the ...
Compute Poisson supply–demand match probability
In a city-day of a two-sided marketplace, customer demand D ~ Poisson(8) and supplier capacity S ~ Poisson(6), assumed independent. (a) Compute P(S >=...
Compute p-values, CIs, and adjust multiples
Hypothesis testing and intervals in practice. Part A (z vs t): You sample n = 15 observations from a population with unknown variance and observe samp...
Compute sample size and test duration correctly
Powering Two Online Experiments: Sample Size, Duration, and Design Defenses You are designing experiments to improve a friend-accept rate metric in a ...
Explain p-value and choose correct test
Technical Screen: P-values and Robust Two-Sample/Paired Tests Context: You are a data scientist evaluating healthcare interventions. Answer in clear, ...
Compute profit and surge break‑even price
Capacity and Break-even Pricing for a Ride-share Service Context: You manage daily capacity and pricing for a ride‑share service. Each driver works an...
Perform no-calculator math accurately and fast
Technical Screen: Mental Math and Estimation Solve quickly without a calculator. For each, show the brief mental shortcut you use. Problems - (a) 37 ×...
Defend MSE over MAE for car prices
Choosing MSE vs. MAE for Car Price Regression (Unscaled USD Target) You are training a regression model to predict car prices in USD. The target varia...
Prove causality for trading metric drop
Goal You need to separate market-driven fluctuations from a product-caused decline in executed_trades per active user around a known release on 2025-0...
Choose threshold under costs and uncertainty
Incentive Targeting: Threshold Selection, Uncertainty, Calibration, and Drift Context: You deploy a model that sends an incentive to predicted positiv...
Derive expectation for two consecutive heads
Waiting Time Until First HH (Two Consecutive Heads) Setup Let T be the number of coin flips required until the pattern HH (two consecutive heads) appe...
Compute optimal stopping in a die-rolling game
Optimal stopping with a fair die (3-roll horizon) You observe outcomes of fair six-sided die rolls (faces 1–6) and may stop after any roll to take the...
Optimize red-ball draw probability, prove optimality
Two-Box Ball Allocation to Maximize Probability of Drawing Red Setup - You have 2 boxes and two colors of balls. - In the 100/100 case: 100 red and 10...
Calculate CI and Test Correlation Under Normality
Inference on a Mean, Significance of a Correlation, and a Normal Quantile Assume standard parametric conditions (normality as stated). Show formulas, ...
Calculate A/B sample size, CI, decision rules
A/B Test Design and Analysis: Signup Funnel You are designing and analyzing a two-arm A/B test for a signup funnel. Assume 1:1 traffic split and indep...
Compute P(Bag B | red) via Bayes
Bayes' Rule: Posterior Probability of the Chosen Bag Setup - There are three bags containing red (r) and green (g) balls: - Bag A: 4 r, 6 g (10 tota...
Explain mixed models and fixed vs random effects
In an applied DS setting, you are modeling an outcome (e.g., watch time per session, conversion, or rating) across multiple entities (e.g., users, cre...
Why does the CLT matter?
Explain the Central Limit Theorem (CLT) and why it matters in data science and machine learning interviews. Then show how you would use the CLT to bui...