- The Farmer
You're a farmer, and are moving a sheep dog, a chicken, and a bag of feed across a river to your new farm. Being so poor, you can only afford a boat which can carry yourself and one other object. Your animals are very hungry; if you leave the sheep dog and the chicken alone, the dog will eat the chicken. If you leave the chicken and feed alone, the chicken will eat the feed. How do you get all three across safely?
- Dollar to Triangle
What is the fewest number of folds it takes to fold a dollar bill into a triangle?
- The Explorer (more of a riddle)
An explorer walks one mile South, one mile East, and one mile North. He finds himself at the exact same spot. He's lost and hungry, so he shoots a bear he finds. What color is the bear?
- Frogs and Lightbulbs
There's a row of 100 lightbulbs, numbered 1-100, and 100 frogs, also numbered. Whenever a frog jumps on a lightbulb, it toggles the bulb on/off. Frog n will jump on every nth bulb (example, the 4th frog will jump on the 4th, 8th, 12th, 16th, etc. bulbs). When all the frogs are done, which bulbs are on?
- Lightbulbs and Switches
You have 3 switches in the basement, labeled A, B, and C. In the attic are 3 lightswitches, 1, 2, and 3. Each switch corresponds to one lightbulb (ie, A might turn on 3, B = 2, and C =1). You can easily figure out which turns on which with 3 trips to the attic. If you're clever, you can do this in two trips. You, however, want to do it in one trip. Can you?
- The Disfigured Checkerboard
If two opposite corners of the checkerboard are removed, can the checkerboard be covered in dominoes? The dominoes are the size of two adjacent squares, and cannot be laid on top of each other.
- Scrambled Marbles
You have three boxes, each with two marbles. There are 2 marble types: black and white. Each box contains two marbles; one box both white, one both black, and one white and one black. Each box is labeled based on its contents, BB, WB, and WW; someone, though, has come back and changed the labels so that all the boxes are mislabeled. You are allowed to take one marble out of a box at a time, without looking inside. What is the least number of marbles you must remove to figure out which box is which?
- The Security Guard
Part I: You work the nightshift as a security guard, and, while getting ready for work, the power keeps going out. You know that in your sock drawer are 10 white socks and 10 black socks (you're too tired to fold them). How many socks do you need to draw from the drawer to ensure you have a pair of socks?
Part II: New company policy: black socks only! How many socks do you need to draw from the drawer to ensure you have a pair of black socks?
- Election Logic
You have three politicians arguing over the outcome of an election: George, Al, and Ralph. They are all saying different things:
- George says Al didn't win.
- Al says neither himself nor George won the election.
- Ralph says that either George or Al won the election.
If only one is telling the truth, who won the election?
- The Tower and the Glass Balls
You are standing in a tower with n floors, holding 2 glass balls. You want to determine the lowest floor at which a glass ball will break. What is the most efficient way of doing this?
Four people are standing in a row facing the same direction, to the right. The person in the back of the line is asked to turn away, to look left. They are all asked to close their eyes while a hat is put on their head randomly. The hats are drawn from a bag of 2 white and 2 black hats. Whenever someone logically deduces what color hat they have on, they get a prize. So they open their eyes ... About a minute passes, and someone says "I know what color my hat is!" Who was it and how did they figure it out?