Skip to main content

Check your intuition: The birthday problem - David Knuffke

2,804,770 Views

13,940 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.

WatchThink Dig Deeper Discuss
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?

About TED-Ed Animations

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

More from Math In Real Life