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Check your intuition: The birthday problem - David Knuffke

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13,668 Questions Answered

TEDEd Animation

Let’s Begin…

Imagine a group of people. How big do you think the group would have to be before there’s more than a 50% chance that two people in the group have the same birthday? The answer is … probably lower than you think. David Knuffke explains how the birthday problem exposes our often-poor intuition when it comes to probability.

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If you adhere to the requirements of the birthday problem (no twins, no leap year, equal chance of any day of the year being a birthday), how many people do you need in a group so that there is a greater-than-average chance that at least two of them share the same birthday?

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TED-Ed Animations feature the words and ideas of educators brought to life by professional animators. Are you an educator or animator interested in creating a TED-Ed Animation? Nominate yourself here »

Meet The Creators

  • Educator David Knuffke
  • Director Biljana Labović
  • Script Editor Eleanor Nelsen
  • Animator Kaitlyn Carroll
  • Sound Designer Weston Fonger
  • Associate Producer Jessica Ruby
  • Content Producer Gerta Xhelo
  • Editorial Producer Alex Rosenthal
  • Narrator Addison Anderson

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