You are an archaeologist that has just unearthed a long-sought triplet of ancient treasure chests. One chest is plated with silver, one with gold, and one with bronze. According to legend, one of the three chests is filled with great treasure, whereas the other two chests both house man-eating pythons that can rip your head off. Faced with a dilemma, you then notice that there are inscriptions on the chests:
Silver Chest: Treasure is in this Chest.
Gold Chest: Treasure is not in this Chest.
Bronze Chest: Treasure is not in the Gold Chest.
You know that at least one of the inscriptions is true, and at least one of the inscriptions is false. Which chest do you open?
There are four people who want to cross a bridge; they all begin on the same side. It is night, and they have one flashlight. A maximum of two people can cross the bridge at one time. Any party that crosses, either one or two people, must have the flashlight with them. The flashlight must be walked back and forth; it cannot be thrown, for example.
Each person walks at a different speed:
What is the minimum amount of time it will take to get all four people across?