On an intriguing urn probability problem

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Authors: Éric Marchand
Cited by: 0

Abstract

We discuss an urn probability problem, which has recently appeared on social media as a puzzle, whose analysis necessitates a prior opinion on the urn contents, and has much pedagogical merit. The derived calculations are intuitively challenging and vary to a significant extent as a function of the given prior distribution. Finally, we contrast solutions for sampling with and without replacement settings, revealing a paradoxical situation with independent draws achieved without replacement and dependent draws achieved with replacement.

Fields of Study & Subjects

Probability and Statistical Research Statistics Education and Methodologies Statistical Distribution Estimation and Applications

Publication details

Journal / source
The Mathematical Gazette
Pages
1–6
Publication date
19 January 2026
Language
EN