Hen, Corn, Fox Challenge

[Timothew]

An cruel dictator arrests a locks up in solitary confinement the 100 most intelligent people in his country. He explains to them that each of them has been given a tattoo on their forehead, either a white circle or a back one, and that there is at least one white (and one black) in the group.

Each person is given a folder with photographs of the other 99 people, their respective circles clearly shown.

The cells contain no mirrors or polished surfaces, there is no way for any of the people to directly observe their own tattoo.

The dictator explains that every day for the next 100 days, the cell doors will unlock between 4pm and 4:30pm. If on any one of those 100 days all (and exactly all) of the people with black tattoos exit their cells, everyone will go free. If at anytime any person with a white tattoo exits their cell (or even opens their unlocked door), everyone will be executed.

On the 40th day at 4pm all the people with black tattoos open their doors and exit their cells, none of those with white tattoos do so.

Having successfully completed the challenge, the dictator releases all the people.

1) How many people had black tattoos
2) How did the people know, and solve the challenge?

First you wait for the chicken to lay an egg.
Hatch the egg.
Train the new chicken to peck at black tattoos.
(This takes 40 days).
On the 40th day, everyone who is pecked by the chicken leaves at 4 PM.
Throw the fox and the chicken over the river.

 

[hasone]

I remeber this from Psyktrek 2.0 an interactive psychology course on CD i got from a family member who got a Ph D in psychology and a scienists degree.

I don't trust psychology any more... it doesn't have anything to offer me. Little Hans is a patented stereotype among with the rest of Freud's patinents...

As for me i saw the horse but i did not start weeping! The thing they do with their patients is making them be confronted with the horse, then beat the patient so much until he start cry... I think that is wicked of them! Wolves...

Freud isn't the same thing as modern psychology. I've been personally against a lot of teaching of Freud in introductory psychology classes for a while now. I find it akin to teaching Aristotle in physics. Important to the history of the science? Yes. Correct? Not necessarily.

 

[Mr. Pedantic]

An cruel dictator arrests a locks up in solitary confinement the 100 most intelligent people in his country. He explains to them that each of them has been given a tattoo on their forehead, either a white circle or a back one, and that there is at least one white (and one black) in the group.

Each person is given a folder with photographs of the other 99 people, their respective circles clearly shown.

The cells contain no mirrors or polished surfaces, there is no way for any of the people to directly observe their own tattoo.

The dictator explains that every day for the next 100 days, the cell doors will unlock between 4pm and 4:30pm. If on any one of those 100 days all (and exactly all) of the people with black tattoos exit their cells, everyone will go free. If at anytime any person with a white tattoo exits their cell (or even opens their unlocked door), everyone will be executed.

On the 40th day at 4pm all the people with black tattoos open their doors and exit their cells, none of those with white tattoos do so.

Having successfully completed the challenge, the dictator releases all the people.

1) How many people had black tattoos
2) How did the people know, and solve the challenge?

If there were only one black circle, then that person would know on the first day from seeing that there were no pictures of people with black; therefore, since there must be at least one, he is the one. Nobody with white circles would leave, because by the above reasoning the person with the black circle would know by the first day he could leave. If they also had a black circle, then the one who really had the black circle would wait until the second day to leave, by the reasoning below.

If there were two black circles, then neither would leave on the first day; for them it would be uncertain whether there were only one black, or two. However, on the second day, because of the reasoning above, they would know that the other person with the black circle could also see one other black circle, and that would be themselves. Nobody with white circles could leave, because they would see two black circles, and they could only make sure they had a black circle on the third day.

This continues for 40 days; every day the number of black circles there must be increases by one, until the 40th day. On the 40th day, given there are 40 circles, each person with black would see 39 other black circles. They know by the fact that nobody left the day before that there must be more than 39 circles, and therefore they are among them. Nobody with white circles would leave because they would see 40 black circles, so they must wait until the 41st day to know for certain whether they are a black or white circle. Therefore, on the 40th day, all 40 people with black circles on their foreheads opens and leaves their cells.

 

[Mystman]

Nobody with white circles would leave because they would see 40 black circles, so they must wait until the 41st day to know for certain whether they are a black or white circle. Therefore, on the 40th day, all 40 people with black circles on their foreheads opens and leaves their cells.

I bow my head in respect, good sir.

Ok I admit, I suck at riddles

 

[Blayz]

We have a winner.