You and nine other individuals

have been captured by super intelligent alien overlords. The aliens think humans look quite tasty, but their civilization forbids eating

highly logical and cooperative beings. Unfortunately, they’re not sure

whether you qualify, so they decide to give you all a test. Through its universal translator, the alien guarding you

tells you the following: You will be placed in a single-file line

facing forward in size order so that each of you can see

everyone lined up ahead of you. You will not be able to look behind you

or step out of line. Each of you will have either a black

or a white hat on your head assigned randomly, and I won’t tell you

how many of each color there are. When I say to begin, each of you must

guess the color of your hat starting with the person in the back

and moving up the line. And don’t even try saying words

other than black or white or signaling some other way,

like intonation or volume; you’ll all be eaten immediately. If at least nine of you guess correctly,

you’ll all be spared. You have five minutes to discuss

and come up with a plan, and then I’ll line you up,

assign your hats, and we’ll begin. Can you think of a strategy guaranteed

to save everyone? Pause the video now

to figure it out for yourself. Answer in: 3 Answer in: 2 Answer in: 1 The key is that the person

at the back of the line who can see everyone else’s hats

can use the words “black” or “white” to communicate some coded information. So what meaning can be

assigned to those words that will allow everyone else

to deduce their hat colors? It can’t be the total number

of black or white hats. There are more than two possible values, but what does have two possible values

is that number’s parity, that is whether it’s odd or even. So the solution is to agree

that whoever goes first will, for example, say “black” if he sees

an odd number of black hats and “white” if he sees

an even number of black hats. Let’s see how it would play out

if the hats were distributed like this. The tallest captive sees three black

hats in front of him, so he says “black,” telling everyone else

he sees an odd number of black hats. He gets his own hat color wrong,

but that’s okay since you’re collectively allowed

to have one wrong answer. Prisoner two also sees an odd

number of black hats, so she knows hers is white,

and answers correctly. Prisoner three sees

an even number of black hats, so he knows that his must be

one of the black hats the first two prisoners saw. Prisoner four hears that and knows that she should be looking for

an even number of black hats since one was behind her. But she only sees one, so she deduces

that her hat is also black. Prisoners five through nine are each

looking for an odd number of black hats, which they see, so they figure out

that their hats are white. Now it all comes down to you

at the front of the line. If the ninth prisoner saw

an odd number of black hats, that can only mean one thing. You’ll find that this strategy works

for any possible arrangement of the hats. The first prisoner has a 50% chance of

giving a wrong answer about his own hat, but the parity information he conveys allows everyone else

to guess theirs with absolute certainty. Each begins by expecting to see an odd

or even number of hats of the specified color. If what they count doesn’t match,

that means their own hat is that color. And everytime this happens, the next person in line will switch

the parity they expect to see. So that’s it, you’re free to go. It looks like these aliens

will have to go hungry, or find some less logical

organisms to abduct.

I would make the tallest one to say the color the he sees in front of him and then the next one would know the color of his hat

It would be easier if he just said the color in front of him. we just need 9 right?

In reality we probably need an hour to convince everyone that this strategy works, so nobody fucks it up

It,s so so good

Aliens: "you have to prove you're rational beings"

Also aliens: "You can't use 99% of possible rational solutions"

Hey ted Ed just in case your having a bad day I love you and please never quit I watch you everyday and you are amazing!

What if everyone's hat is white?????

What if all of them just RAN away

ITS not against the rule isnt it?