full transcript

From the Ted Talk by Jennifer Lu: Can you solve the counterfeit coin riddle?

Unscramble the Blue Letters


If they don’t, draw a plus on the three unrkaemd coins if they’re hveeiar, or a minus if they’re lighter. Now take two of the newly marked coins and wgieh them against each other. If they balance, the third coin is fake.

Otherwise, look at their makrs. If they are plus coins, the heavier one is the ioomtspr. If they are mkraed with minus, it's the lighter one.

But what if the first two piles you way don't balance? Mark the coins on the heavier side with a plus and those on the lighter side with a minus. You can also mark the remaining four coins with zeros, since you know the fake one is already somewhere on the scale. Now you'll need to think strategically so you can remove all remaining ambiguity in just two more ways.

Open Cloze


If they don’t, draw a plus on the three ________ coins if they’re _______, or a minus if they’re lighter. Now take two of the newly marked coins and _____ them against each other. If they balance, the third coin is fake.

Otherwise, look at their _____. If they are plus coins, the heavier one is the ________. If they are ______ with minus, it's the lighter one.

But what if the first two piles you way don't balance? Mark the coins on the heavier side with a plus and those on the lighter side with a minus. You can also mark the remaining four coins with zeros, since you know the fake one is already somewhere on the scale. Now you'll need to think strategically so you can remove all remaining ambiguity in just two more ways.

Solution


  1. impostor
  2. marked
  3. unmarked
  4. weigh
  5. heavier
  6. marks

Original Text


If they don’t, draw a plus on the three unmarked coins if they’re heavier, or a minus if they’re lighter. Now take two of the newly marked coins and weigh them against each other. If they balance, the third coin is fake.

Otherwise, look at their marks. If they are plus coins, the heavier one is the impostor. If they are marked with minus, it's the lighter one.

But what if the first two piles you way don't balance? Mark the coins on the heavier side with a plus and those on the lighter side with a minus. You can also mark the remaining four coins with zeros, since you know the fake one is already somewhere on the scale. Now you'll need to think strategically so you can remove all remaining ambiguity in just two more ways.

Frequently Occurring Word Combinations


ngrams of length 2

collocation frequency
heavier side 3
false coin 2
unmarked coins 2
lighter side 2
previously heavier 2

ngrams of length 3

collocation frequency
previously heavier side 2

Important Words


  1. ambiguity
  2. balance
  3. coin
  4. coins
  5. draw
  6. fake
  7. heavier
  8. impostor
  9. lighter
  10. mark
  11. marked
  12. marks
  13. newly
  14. piles
  15. remaining
  16. remove
  17. scale
  18. side
  19. strategically
  20. unmarked
  21. ways
  22. weigh
  23. zeros