One absentminded ancient philosopher forgot to wind up his only clock in the house. He had no radio, TV, telephone, internet, or any other means for telling time. So he traveled on foot to his friend’s place few miles down the straight desert road. He stayed at his friend’s house for the night and when he came back home, he knew how to set his clock.
How did he know?
Wednesday, September 9, 2009
DEATH
You've been sentenced to death in an obscure foreign country which has a strange law. Before the sentence is carried out, two papers -- one with "LIFE" written on it and one with "DEATH" written on it -- are folded up and placed in a hat. You are permitted to pick out one of the papers (without looking), and if you choose the one with "LIFE" written on it, you are set free. Otherwise, the death sentence is carried out. On this occasion, an enemy of yours, bent on your demise, has substituted the paper with "LIFE" written on it with another one with "DEATH" written on it. Now both the papers from which you have to pick out are written “DEATH” on them. This person informs you of what he has done and that you are doomed to die. You are not permitted to speak to anyone about this misdeed, nor will you have a chance to switch the papers or the hat yourself in time. How will you avoid certain death?
Lady And Tiger II
If a lady is in Room I, then the sign on the door is true, but if a tiger is in it, the sign is false. In Room II, the situation is the opposite: a lady in the room means the sign on the door is false, and a tiger in the room means the sign is true. Again, it is possible that both rooms contain ladies or both rooms contain tigers, or that one room contains a lady and the other a tiger. The signs on the doors of the rooms are as follows:
Room1:BOTH ROOMS CONTAIN LADIES
Room2:BOTH ROOMS CONTAIN LADIES
Which door should you open (assuming, of course, that you prefer the lady to the tiger)?
Solution:
Since the signs say the same thing, they are both true or both false. Suppose they are true; then both rooms contain ladies. This would mean in particular that Room II contains a lady. But we have been told that if Room II contains a lady, the sign is false. This is a contradiction, so the signs are not true; they are both false. Therefore, Room I contains a tiger and Room II contains a lady, so you should choose Room II.
Room1:BOTH ROOMS CONTAIN LADIES
Room2:BOTH ROOMS CONTAIN LADIES
Which door should you open (assuming, of course, that you prefer the lady to the tiger)?
Solution:
Since the signs say the same thing, they are both true or both false. Suppose they are true; then both rooms contain ladies. This would mean in particular that Room II contains a lady. But we have been told that if Room II contains a lady, the sign is false. This is a contradiction, so the signs are not true; they are both false. Therefore, Room I contains a tiger and Room II contains a lady, so you should choose Room II.
Lady And Tiger
This is the first puzzle of a series of classic "Lady or the Tiger" puzzles. You have to choose between two rooms. Each of them contains either a lady or a tiger, but it could be that there are ladies in both rooms, or tigers in both rooms, or one could contain a lady while the other contained a tiger. There are signs on the doors of the rooms:
Room 1:IN THIS ROOM THERE IS A LADY, AND IN THE OTHER ROOM THERE IS A TIGER .
Room 2:IN ONE OF THESE ROOMS THERE IS A LADY, AND IN ONE OF THESE ROOMS THERE IS A TIGER .
One of the signs is true, but the other one is false. Which door would you open (assuming, of course, that you preferred the lady to the tiger)?
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