Data Scientist Statistics & Math Interview Questions
Practice 455 real Statistics & Math interview questions for Data Scientist roles. From companies including Meta, Capital One, Google, Amazon, Uber.
"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."
Derive mean and variance of x̄
Let \(X_1, X_2, \dots, X_n\) be random variables, and define the sample mean as \(\bar X = \frac{1}{n}\sum_{i=1}^n X_i\). 1. Assume the variables are ...
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...
Estimate laptops in an office
Give a back-of-the-envelope estimate for how many laptops are physically present in a typical corporate office at a given moment. State your assumptio...
Calculate Conversion Lift CI
In an A/B test, the control group had 1,000 users and 120 conversions. The treatment group had 1,000 users and 150 conversions. Using a normal approxi...
Estimate total attendance from size-biased reservation sample
You run a restaurant with N = 10,000 reservations in a day. Each reservation j has: - Reserved party size: \(R_j\) (positive integer) - Actual number ...
Sketch distributions and compare mean/median/mode
Sketching distributions and comparing mean, median, and mode This is a conceptual statistics question with two independent scenarios. For each, you sk...
Why use the t-statistic?
In an A/B test or any mean-comparison setting, explain why the t-statistic is a useful measure. Your answer should cover: 1. What the t-statistic meas...
Why is the t-statistic useful
In classical hypothesis testing (e.g., a one-sample or two-sample mean test), explain: Question 1. What is the t-statistic and how is it computed? 2. ...
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...
Analyze data duplication effects in linear regression
OLS With Duplicated Observations: Estimator, Variance, and Inference Pitfalls Context: You have the linear model y = Xβ + ε with full-rank X ∈ ℝ^{n×p}...
Analyze EV, arbitrage, and bet sizing across games
Betting Games: EV, Variance, Arbitrage, and Sizing Context You will be shown payout tables or odds for three independent games. Your task is to quickl...
Explain Bootstrap and Prove Uniformity
You are interviewing for a Data Scientist role. Answer the following statistics-theory prompts: 1. What is the bootstrap, when would you use it, and c...
Estimate constant under absolute loss
Suppose you have observed target values \(y_1, y_2, \dots, y_n\), and you want to fit the simplest possible model that predicts the same constant valu...
Explain and resolve Simpson’s paradox
Define Simpson’s paradox and construct a concrete numeric example where group-wise success rates favor treatment in each subgroup but the aggregate ra...
Answer four core statistics questions
Problem set (timed) Answer the following four questions. 1) Covariance of order statistics Let \(X\) and \(Y\) be independent \(\mathrm{Unif}(0,1)\). ...
Compute probability match lasts 5 games
Two players play independent games of table tennis. - Player A wins each game with probability \(p\) (constant across games). - They play a best-of-5 ...
Compute credit-card portfolio profit and breakeven
A bank is evaluating a new credit card. Segments: A: 30,000 customers, capture rate 20%, avg annual spend per captured customer = $100,000. B: any pop...
Calculate profit and break-even across pricing models
Unit Economics and Break-even Analysis for a Cloud-Storage Startup You are analyzing a cloud-storage startup that currently charges unit-based pricing...
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 ...
Explain BLS vs CLS; compute t-stats
Part A — Concepts: Define Brand Lift Study (BLS) vs Conversion Lift Study (CLS) in ads measurement. List key bias/variance sources for each (e.g., non...