Question: How many people do you need to have the odds be in favor (at least 50% chance) of two people having the same birthday?
Answer: At least 23 people.
For an explanation visit http://en.wikipedia.org/wiki/Birthday_problem
Question: A man is stuck on an island with his best friend and a fisherman. The fisherman and his best friend go off to catch food while he builds a hut. The fisherman returns alone with some salmon he had prepared. His best friend had fallen off a cliff.
After he is rescued from the man goes to a diner and he orders salmon. He eats his meal, he pulls out a gun and commits suicide. Why does he do this?
Answer: He realizes what he had eaten on the island was not in fact salmon, but rather his best friend.
Question: There is a basket full of hats. 3 of them are white and 2 of them are black. There are 3 men Tom, Tim, and Jim. They each take a hat out of the basket and put it on their heads without seeing the hat they selected or the hats the other men selected. The men arrange themselves so Tom can see Tim and Jim's hats, Tim can see Jim's hat, and Jim can't see anyone's hat.
Tom is asked what color his hat is and he says he doesn't know.
Tim is asked the same question, and he also doesn't know.
Finally, Jim is asked the question, and he does know.
What color is his hat?
Answer: The hat is white. If Tom doesn't know his hat color then the other two men's hats cannot be both black otherwise he would know his is white. When Tim doesn't know his hat color either, that means Jim's hat could not be black otherwise Tim would have to know his hat was white to fulfill the information discovered through Tom's answer.
Question: If you have an 11 minute and 13 minute hourglass, how can you accurately time 15 minutes?
Answer: Start both hourglasses then when the 11 minute hourglass has finished immediately flip it again. When the 13 minute hourglass runs out the 11 minute hourglass will have 9 minutes left, so flip it and it will last another 2 minutes, 13 minutes + 2 minutes = 15 minutes.
Question: You have a glass of water that looks about half full. How can you tell, only using the glass of water itself, if the glass is half full or not?
The glass is a right cylinder.
Answer: Tip the glass of water until the water reaches the rim of the glass and if the water lines up perfectly with the bottom rim of the glass, it is half full.