The SAT Question Everyone Got Wrong

The SAT Question Everyone Got Wrong

Formal & Physical Sciences Mathematics PBMathematicsPBMGeometry
🎙 Veritasium 👥 21.2M 📅 November 30, 2023 ⏱ 18 min 👁 18.5M 📄 science communication 🧭 2026-09-03
Available in: English (current) Français

Keywords

SATcoin rotation paradoxrevolutionsidereal daymathematics education

Summary

The video recounts the 1982 SAT question that all test-takers got wrong because the correct answer was not among the options. The problem involved a small circle rolling around a larger circle, and the intuitive answer of 3 rotations was incorrect; the actual answer is 4. The video explains the coin rotation paradox, demonstrating that a circle rolling around another circle of equal size makes two rotations, not one. It provides a general solution: the number of rotations equals the ratio of circumferences plus one for the circular path. The video also explores the ambiguity of the term ‘revolution’, which can yield different answers depending on the definition used. It features an interview with Doug Jungreis, one of the students who alerted the College Board to the error, leading to the question being nullified. The video extends the concept to astronomy, explaining the difference between solar and sidereal days, and how the extra rotation accounts for the difference. It concludes with a discussion of the impact of rescoring on students’ scores and the declining role of the SAT in college admissions.

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Critical Evaluation

Value of the Information & Strength of the Argument

The video provides a clear and compelling explanation of a counterintuitive mathematical phenomenon. The argumentation is solid, building from a simple demonstration with coins to a formal proof using the concept of rolling without slipping. The use of visual aids and real-world examples enhances understanding. The video also adds historical context and interviews, which strengthens its credibility. The explanation of the general principle and its application to astronomy demonstrates the broader significance of the concept.

Scientific Rigor, Source Quality, Title Accuracy

The video demonstrates high scientific rigor by citing primary sources, including a New York Times article from 1982 and a Scientific American piece. The mathematical explanations are accurate and well-illustrated. The title accurately reflects the content, and the video does not overstate its claims. The inclusion of an interview with one of the students who identified the error adds authenticity. The video also acknowledges the ambiguity of the term ‘revolution’, showing a nuanced understanding of the issue.

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Title / Content Match

The title accurately reflects the content, which focuses on the SAT question that was flawed and the mathematical paradox behind it.

Quality & Reliability

9/10

The video presents a well-researched historical account of the 1982 SAT error, featuring interviews with one of the students who identified the mistake, and provides rigorous mathematical explanations with visual demonstrations. The claims are supported by references to primary sources (New York Times article, Scientific American) and standard mathematical principles.

Key Moments

Cited Sources

Concurring Sources

Dissenting Sources

  • Alternative interpretations of 'revolution' — The video acknowledges that the term 'revolution' is ambiguous, and depending on the definition, the answer could be 1, 3, or 4. This is not a contradiction but a nuance in the problem's wording.

External References

Contribution & Novelties

The video provides a comprehensive and accessible explanation of the coin rotation paradox, going beyond the simple ‘add one’ rule to a formal proof based on the distance traveled by the center of the rolling circle. It also connects the mathematical concept to real-world applications in astronomy, specifically the difference between solar and sidereal time, which is a novel and insightful link. The historical context, including interviews and primary sources, adds depth and credibility.

Pour aller plus loin :

  • Coin rotation paradox — The Wikipedia article provides a detailed mathematical treatment of the paradox.
  • Sidereal time — Explains the concept of sidereal time and its importance in astronomy.
  • Rolling without slipping — The concept of rolling without slipping is central to the proof presented in the video.
  • SAT — The history and impact of the SAT exam, including the 1982 incident.

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Radar Profile

The radar profile shows high scores in information quantity, quality, and reliability, with a slightly lower technical level, indicating that the video is accessible to a broad audience while maintaining scientific accuracy. The balance between these scores suggests a well-crafted educational piece.

Reliability 9/10

💬 Très positif. Sur les 30 commentaires analysés, les spectateurs expriment une forte appréciation pour la clarté des explications et la démonstration visuelle, avec de nombreux commentaires soulignant l'étonnement et la satisfaction d'avoir enfin compris le paradoxe.