Waste less time on Facebook — follow Brilliant.

Math is one of my favorite subjects. Their are so many different problems and difficulty's to it. If you have any challenging math problems write them and I can help solve!!!

Note by Arianna Williams
4 years ago

No vote yet
6 votes


Sort by:

Top Newest

Here's a logic problem I yanked from skorks that I had some fun with. Logic is part of math, right? Or the other way around. Anyway:

There is a village full of people. One day the priest gathers all the villagers together and declares that their God has told him that some among the villagers are sinners. All sinners will be marked with a sign on their forehead so that all other people will be able to see if a person is a sinner or not, but noone will know if there is a mark on their own forehead. Furthermore, the mark will not be visible in the mirror and one person is forbidden from telling another if they are a sinner. The villagers must work out which among them are sinners at which point all sinners are to leave the village. The village has been given one week and if at the end of the week, there are still sinners present, the whole village will be destroyed.

The villagers go about their own business during the day, however the whole village gathers in the square at the end of every day so that everyone can see if there are still any sinners left among them. After the third such gathering all the sinners pack up their stuff and leave the village.

How many sinners were there? How did you arrive at that number?

Christopher Johnson - 4 years ago

Log in to reply

Yes, i also think 3 sinners.

This is my thinking process. Lets say there are only one sinner, then he would show up and know that it was him, so he would leave at first day.

Then two sinners, they would see one other sinner at the fist day, so when they show up the second day and see that the other sinner hasn't left, then they know that there must be more sinners in the group but they can only see one, so therefore they themselves are sinners.

And this process goes on, so if there where 100 sinners it would take 100 days and then all 100 sinners would leave.

Log in to reply

Yeah me too.

Fatin Farhan - 4 years ago

Log in to reply

I think 3 sinners

Fatin Farhan - 4 years ago

Log in to reply


Problem Loading...

Note Loading...

Set Loading...