# Mind Puzzles

A variety of puzzles and brain teasers from physics, chemistry, math, and science. These puzzles will spice up your mind.

Puzzle #1: Hens and Eggs

A farmer has 100 hens, numbered from 1 up to and including 100. Only the hens with the numbers 13 up to and including 48 each lay one egg. How many of the hens have not laid an egg?

Puzzle #2: Dish with Three Oranges

There is a dish with three oranges. Suppose that you take two oranges from the dish. How many oranges do you have?

Puzzle #3: Knights, Knaves and Normals

Imagine you are on an island called Texel, with inhabitants that look the same from the outside, but differ in their truthfulness. We distinguish the following types:

Knights, who always tell the truth.
Knaves, who never tell the truth.
Normals, who sometimes tell the truth and sometimes lie.
Assume you meet one of these inhabitants, and he tells you: “I’m no Knight”. Then, of what type is inhabitant?

Puzzle #4: Color of the Bear

A hunter leaves his cabin early in the morning and walks one mile due south. Here he sees a bear and starts chasing it for one mile due east before he is able to shoot the bear. After shooting the bear, he drags it one mile due north back to his cabin where he started that morning. What color is the bear?

Puzzle #5: Milk and Water Mixture

Consider two cans, the first containing one liter of milk and the second containing one liter of water. Suppose you take one cup of milk out of the first can and pour it into the second can. After mixing, you take one cup of the mixture from the second can and pour it back into the first can. Which of the following statements holds now?

Puzzle #6: Alice, the Lion and the Unicorn

One day Alice meets the Lion and the Unicorn in the Forest of Forgetfulness. She knows that the Lion lies on Mondays, Tuesdays, and Wednesdays, and tells the truth on the other days of the week. The Unicorn, on the other hand, lies on Thursdays, Fridays, and Saturdays, but tells the truth on the other days of the week. Now they make the following statements to Alice:

Lion: Yesterday was one of my lying days.
Unicorn: Yesterday was one of my lying days too.
What day is it?