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Statistics & Math questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master statistics & math interviews.

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This is a easy difficulty Statistics & Math question, commonly asked during Technical Screen rounds at TikTok.

What role is this question designed for?

This question is commonly asked for Data Scientist candidates at TikTok during technical interviews.

Calculate Expected Draws for X > 0.8 in Uniform(0,1)

Last updated: Mar 29, 2026

Quick Overview

This question evaluates a candidate's understanding of basic probability concepts and expected value in the context of random sampling. It is commonly asked to gauge statistical intuition about sampling and rare-event frequency, falls under the Statistics & Math category, and tests conceptual understanding rather than practical implementation.

TikTok

Aug 4, 2025, 10:55 AM

Data Scientist

Technical Screen

Statistics & Math

Scenario

Quick probability check during a first-round screen to gauge statistical intuition.

Question

Let X ~ Uniform(0, 1). You draw independent samples X1, X2, … from this distribution.

On average, how many draws are needed until you first observe a value greater than 0.8?

Assumption: Each draw is independent and identically distributed (i.i.d.).
Hint: Model the number of trials with a geometric distribution.

Solution

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