Riddle #93

Question: There is a prison with 100 prisoners, each in separate cells with no form of contact. There is an area in the prison with a single light bulb in it. Each day, the warden picks one of the prisoners at random, even if they have been picked before, and takes them out to the lobby. The prisoner will have the choice to flip the switch if they want. The light bulb starts off.

When a prisoner is taken into the area with the light bulb, he can also say "Every prisoner has been brought to the light bulb." If this is true all prisoners will go free. However, if a prisoner chooses to say this and it's wrong, all the prisoners will be executed. So a prisoner should only say this if he knows it is true for sure.

Before the first day of this process begins, all the prisoners are allowed to get together to discuss a strategy to eventually save themselves.

What strategy could they use to ensure they will go free?

Riddle Discussion

By: Soraphis on 16/11/15

even if they live forever (not aging, but can be killed) theres no way of ensure they will go free. because the warden picks them by random it is possible (very unlikely but possible) that one person is not chosen at all

By: whenevertobe on 1/2/15

I don't understand this. If they do this correctly, one day per prisoner, The shortest possible amount of time they can do this in is in 198 days. The chances that the special prisoner will be picked randomly every other day and that every other prisoner will be picked only once (in order for the shortest amount of time to work) is 1 in 1 with 240 zeros after it, in other words, it won't happen. Chances are he will only be picked one out of a hundred times. So chances are that for him to be picked one hundred times is 100 * 100, which is 10,000 days. That's 27 years. Ok, I guess it's possible.

Similar Riddles

In the sink (medium)

Question: Why is the man standing in the sink?

Question: Listen closely, for these for riddles are all connected. 1. How do you put a giraffe in the refrigerator? 2. How do you put an elephant in the refrigerator? 3. The lion king is having an animal conference, and all animals attend except one. Which animal does not attend? 4. You are on a stranded island that is inhabited by crocodiles. How do you get across without getting eaten alive?

Question: A man is found dead on a Sunday morning. His wife calls the police immediately. The police question the wife and staff. The wife said she was asleep, the cook said he was cooking breakfast, the gardener said she was picking vegetables, the butler said he was cleaning the closet, and the maid said she was getting the post. The police immediately arrested the murderer.Who was the murderer?

Riddle #1674 (medium)

Question: Two men, Watson and Holmes, are out in the extremely dry forest. They are completely surrounded by a large forest fire on one side and a dangerous cliff on the other. The wind is blowing the forest fire towards them and the cliff. The fire will reach them in about one day.

Holmes turns to Watson, "I have matches, berries, and enough water for a day. We aren't going to die." How can they avoid getting swallowed up by the forest fire?

Riddle #3081 (medium)

Question: It is Halloween and your friends dare you to go into a haunted house. You creep up to the door, a little scared wondering what is behind the door. You go in and there is a long hallway leading out into a dark musty room with three doors. You're kind of scared once you are inside. You try to turn back, to get back outside, but when you turn around the door is closed and locked. You yell for help but there is only silence. The room is dark and you look for a light source. You see a light switch and try to turn it on. Sadly the power is out. You are terrified but have no choice but to follow the long hallway to the three doors in the pitch black. Behind one door is a bottomless pit with no end. Behind another door is an electric chair which you must sit in. Behind the last door is a pool full of acid. You must go in one of the rooms to the danger. Which one should you go through?