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Can you solve the bridge riddle? - Alex Gendler

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TEDEd Animation

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Taking that internship in a remote mountain lab might not have been the best idea. Pulling that lever with the skull symbol just to see what it did probably wasn’t so smart either. But now is not the time for regrets because you need to get away from these mutant zombies...fast. Can you use math to get you and your friends over the bridge before the zombies arrive? Alex Gendler shows how.

Additional Resources for you to Explore

This is the ‘bridge and torch’ problem, an example of the wider category of ‘river crossing puzzles.’ Read about other examples and their history here. Variations of the problem have appeared for decades, each with different numbers and times, but it is possible to work out a formal mathematical solution for any of the values you plug in.

Variations of the puzzle have even been used to test computer programming languages for their usefulness in problem-solving. Can you think of any other reason you may want to challenge yourself with similar puzzles?

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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 Alex Gendler
  • Director Outis
  • Composer Cem Misirlioglu
  • Narrator Addison Anderson

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