Can you solve the buried treasure riddle? – Daniel Griller
100 Comments


After a massive storm tears
through the Hex Archipelago, you find five grizzled
survivors in the water. Shivering their timbers, they explain that they’re the former crew
of the great pirate Greenbeard, who marooned them
after they tried to mutiny. Each was bound up in a different
spot on a small island, until the storm washed them out to sea. In gratitude for saving them,
they reveal a secret: the island they were on is also where
Greenbeard has buried his treasure hoard. But when the sailors try to describe
the island, something seems off. All agree it was flat and barren with no
prominent features except for some trees. Yet each pirate claims they saw
a different number of trees, ranging from two to six. The pirate who saw two trees says the
treasure was buried right at his feet. When you fly your hot air balloon
over the area to investigate, you see hundreds of small islands,
each with exactly six trees. The next storm will be here soon, so you’ll have to hurry
and narrow your search. What does the island with Greenbeard’s
treasure look like from the sky? And where will the treasure be
on that island? Pause here if you want
to figure it out for yourself! Answer in 3 Answer in 2 Answer in 1 It might seem like the pirates
are delirious from dehydration. But that’s not what’s going on. Remember, each was confined
to a separate point on the island, and no two of them could see
the same number of trees. That means that for all but one pirate,
something was blocking their view. And since there are no other
features on the island, that something could only
have been other trees. A pirate would see fewer trees
when two or more fell along a straight line
from their vantage point. So we need to find the island where five different pirates standing
in different spots would each see a
different number of trees. Virtually every island has a position
from which you can see six trees. And on most islands there’s a
position where 5 trees can be seen by standing in line with two of them. It turns out that the hardest locations
to find are those with fewer visible trees precisely because they require more trees
to line up with the viewer’s position. So how can we see just two trees? One way would be if all the trees
were lined up in single file, such as on this island. Then, you could stand at the end
of the line and see one, stand in the middle and see two, or stand anywhere else and see all six. But there’s no place from
which you can see only three, four, or five, so one straight line of trees is out. So what about two lines of trees? So long as the lines aren’t parallel
and they intersect over land, there’ll always be a position
where the two lines converge from which you could
see exactly two trees. And if they’re grouped two and four, or three and three, there are many arrangements in which
you could also see three, four, five, and six trees. Fortunately for us, there’s only
one island in the archipelago with two non-parallel lines of trees, and it’ll be buried at the intersection
of the two lines. You land on this island and dig up a chest
containing a massive pile of tree seeds, ready for planting. Was this treasure really worth
all that trouble? That’s a matter of perspective.

100 thoughts on “Can you solve the buried treasure riddle? – Daniel Griller

  1. If you want to practice more problem-solving for free, head to https://brilliant.org/TEDEd/. If you want to sign up for a "premium" account, hurry! The first 833 of you to visit that link will receive 20% off the annual premium subscription. Thanks to Brilliant for supporting this video!

  2. This riddle is so misleading. Can it not be the case that a pirate is facing the sea near the edge of the island and has only two trees (or 3/4/5/6) between him and sea ?
    I think the riddle should of stated that the only way someone could have seen a number less than 6 tress was by other trees blocking them !

  3. At 3:18 you showed the group of 2 and 4 which is also correct and which was also my solution so there are 2 possible solutions and not just one. I'd love if you put in description or top comment that there are 2 possible solutions.

  4. OMG OMG OMG OMG!!!!! I LOOOOOOOOOOOOOOOOOVE DEM RIDDLES!!!! I'VE SEEN ALL SO MANY TIMES!!!!!!!!!! YAAAAAAAAAAAAAAAAAY!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

  5. In your example at 3:30, a pirate could be in the bottom left and see only 2 trees, so your busted your own riddle with your own example?

  6. It's important to clarify that any 4,2 configuration with the intersection of the two lines on land and at least small epsilon – patches for each tree would do (epsilon is relatively small, depends on the width of the trees). On the other hand, only very special 3,3 configurations are valid, those that are also an arrangement in which there are three concurrent lines of 2 trees each. Assuming a uniform distribution of probability, 4,2 seems a lot more likely to be the answer.

  7. Um you forgot the part where THE PIRATE IS TIED TO THE TREE! This is the only one you guys didn't really think thru

  8. Again so much setup but you manage to not make it clear – the pirates didn't have to be tied to trees but you showed a graphic that was misleading at first – I also went back to look at it again. As well, there are far more arrangements of islands with 2 non parallel rows of 3 trees in which you cannot have a pirate able to see 3 trees, than there are arrangements of 2 non parallel rows of 3 trees each in which one of the pirates can only see 3 trees. I like riddles but I like it better when they are concisely defined and answered correctly.

  9. so you guys didn't watch or listen to the part where the storm washed them out to sea? or the first sentence that says they were in the water?

  10. Wait. None of these pirates fidgeted? Not once while being tied up? They all just stayed in the exact-same spot until the storm?

  11. Oh… Green beard , like a nature pirate. Wait then why would the crew mutiny, the dude just wants to plant some trees.

  12. I thought there would be a certain number of trees to each pirate’s back, where he couldn’t see them, but that works too

  13. I would like to point out the fact that at 0:27 it shows 3 pirates tied to trees. If they showed that the pirates were not bound so closely to trees… I still doubt that I would've been able to solve this. But with them being tied to trees (or so I thought) I raised the question (only from the theory where they are ACTUALLY TIED TO TREES) that one of them could not see 6 trees from being already bound to one. My solution to the problem (still the one where they are tied to trees) is to find the island with a total of 7 trees and not just six. Needless to say the answer was wrong because THE FLIBBIN PIRATES WERE NOT TIED UP TO THE TREES IN THE FIRST PLACE. I might have wasted my time overthinking all of what the question was asking but now I'm just wasting my time writing this.

  14. I Love this channel. I learned new things explore the world and history. Thank you to the creators of Ted Ed for creating this channel it helped a lot of people who wanted to explore and learn more things.

    I hope that their will be more videos to come

  15. what if those pirate facing different direction? i assume those who tie up with a tree cant see tree behind them…. this is a disaster with leak of information

  16. I paused the video at 1:27 and decided to solve the riddle. Here is my answer. If I’m correct, then the pirate who saw 2 trees must have been on an island with the trees all lined up in a row. From where he sat, it would look there were only two trees, because the other trees were obscured by the trees in front of him. This means that wherever these two lines of trees intersect, would be where the treasure lies.

  17. Let's look at the bigger logic error:

    Why would Captain Greenbeard leave his treasure on the same island as mutineering pirates?

  18. Rule 2: shape of trees isn't important, so i assume they can't obstruct each other
    Rule 3: they canot move but rhey can look 360? So everyone must see 6 trees

    3 sec after: the trees can obstruct other trees
    My mind: really?

  19. This riddle was explained very poorly and the graphics actually served to confuse instead of inform.

  20. the trees must all be in a straight line! but i don't know which two trees the one who only saw two was between :<

  21. took me a long time to figure it out !!!! I also first assume parallel lines and then non parallel instead there is not a 100% solution. it's like uncertainty principle, if you change the postion of pirates , position of trees doesn't remain same

  22. UNTIL THE STORM WASHED THEM OUT TO SEA

    the storm broke them free from the trees people and they were all scattered around the island

    Comon sense isnt so common anymore

  23. there are only five pirates which mmeans that the islnad had five tress and on that island has the treasure 🙂

  24. The question specifies the shape of the tree is not important. However, if the tree is tilting in different directions, they may not be able to block each other.

  25. Green beard is actually a baş guy because he buried the seeds with a chest there is no way those seeds would grow and top of that he tried to drown other pirates that know where the treasure is

  26. This one wasn’t that good. Each of the Pirates can look up to see their own tree counting that as one of the trees. Based off the information that was given, it’s inferred that all of them were tied to trees, or else what restricts the other ones movement and prevents his bound and gagged body from washing away to the sea still bound and gagged?

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