full transcript

From the Ted Talk by Daniel Finkel: Can you solve the jail break riddle?

Unscramble the Blue Letters


The length of the fuse may not tell you anything, but you do know the fuses take exactly 60 seconds to burn from end to end. Here’s the key insight: If you start a fuse on one side and it burns for 30 seconds, there’ll still be 30 seconds of fuse left. If you had started it from the other end, it would’ve reaehcd the exact same spot in thirty seconds. That means that if you lit it from both ends simultaneously, it would burn out in pecilsrey 30 seconds.

But how will you time the last fifteen?

That’ll have to come from the second fuse. If it were a 30 second fuse, you’d be able to use that same trick again to double the burning seepd and make it last exactly 15 seconds. And, you realize, you can setrhon the second fuse by lighting one end of it at the same time as you lhgit the first. At the monmet the first burns out, you’ll be left with 30 scodens on the second fuse.

Open Cloze


The length of the fuse may not tell you anything, but you do know the fuses take exactly 60 seconds to burn from end to end. Here’s the key insight: If you start a fuse on one side and it burns for 30 seconds, there’ll still be 30 seconds of fuse left. If you had started it from the other end, it would’ve _______ the exact same spot in thirty seconds. That means that if you lit it from both ends simultaneously, it would burn out in _________ 30 seconds.

But how will you time the last fifteen?

That’ll have to come from the second fuse. If it were a 30 second fuse, you’d be able to use that same trick again to double the burning _____ and make it last exactly 15 seconds. And, you realize, you can _______ the second fuse by lighting one end of it at the same time as you _____ the first. At the ______ the first burns out, you’ll be left with 30 _______ on the second fuse.

Solution


  1. shorten
  2. speed
  3. light
  4. moment
  5. seconds
  6. reached
  7. precisely

Original Text


The length of the fuse may not tell you anything, but you do know the fuses take exactly 60 seconds to burn from end to end. Here’s the key insight: If you start a fuse on one side and it burns for 30 seconds, there’ll still be 30 seconds of fuse left. If you had started it from the other end, it would’ve reached the exact same spot in thirty seconds. That means that if you lit it from both ends simultaneously, it would burn out in precisely 30 seconds.

But how will you time the last fifteen?

That’ll have to come from the second fuse. If it were a 30 second fuse, you’d be able to use that same trick again to double the burning speed and make it last exactly 15 seconds. And, you realize, you can shorten the second fuse by lighting one end of it at the same time as you light the first. At the moment the first burns out, you’ll be left with 30 seconds on the second fuse.

Frequently Occurring Word Combinations


ngrams of length 2

collocation frequency
electric fence 2
home free 2


Important Words


  1. burn
  2. burning
  3. burns
  4. double
  5. ends
  6. exact
  7. fifteen
  8. fuse
  9. fuses
  10. key
  11. left
  12. length
  13. light
  14. lighting
  15. lit
  16. means
  17. moment
  18. precisely
  19. reached
  20. realize
  21. seconds
  22. shorten
  23. side
  24. simultaneously
  25. speed
  26. spot
  27. start
  28. started
  29. time
  30. trick