A friend of mine passed along some puzzlers, and now I pass them on to you. The answers will be in the comments, so you needn't spoil yourself by accident.
1. You're on the old TV game show "Let's Make a Deal." Monty Hall presents you with a choice of three doors. Behind one of the doors is a shiny new car. Behind each of the other doors is a goat. You choose Door Number One. Monty Hall, knowing which door conceals the car, opens Door Number Three and reveals one of the goats. Then he asks if you would like to switch your choice to Door Number Two. If you changed your choice, would you be more likely or less likely to win the new car, or would your chances stay the same?
2. There is three things wrong with this sentance. What are they?
3. You're sailing on a small, closed lake when you throw a 50-pound anchor over the side, and it sinks right to the bottom. Does the water level rise, go down, or stay the same?
4. You're driving over a steep hill. The uphill side is one mile long, and the downhill side is one mile long. Going uphill, your average speed is 30 miles per hour. What speed must you average on the downhill side to have an average speed of 60 miles an hour going up and down?