10 questions. I’ll give you a week to get them all right, before posting answers. Good luck

A man is standing in front of a painting of a man, and he tells us the following: “Brothers and sisters have I none, but this man’s father is my fathers son”. Who’s on the painting?

His father

He himself

His son

It is dark in my bedroom and I want to get two socks of the same color from my drawer, which contains 24 red and 24 blue socks. How many socks do I have to take from the drawer to get at least two socks of the same color?

2

3

24

47

48

Imagine you are on an island called Texel, with inhabitants that look the same from the outside, but differ from inside (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?

Knight

Knave

Normal

Indeterminable

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?

Black

Brown

White

Gray

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9’s are used in these numbers?

10

11

19

20

In a city called Veldhoven the following facts are true:

No two inhabitants have exactly the same number of hairs.

No inhabitant has exactly 40360 hairs.

There are more inhabitants than there are hairs on the head of any one inhabitant.

What is the largest possible number of inhabitants of Veldhoven?

0

40359

40360

40361

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 one of the following statements holds now?

There is more water in the first can than milk in the second can.

There is less water in the first can than milk in the second can.

There is as much water in the first can as there is milk in the second can.

None of the previous statements holds.

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?

Sunday

Monday

Tuesday

Wednesday

Thursday

Friday

Saturday

A Cretan named Epimenides once said to a fellow Cretan: “All Cretans are liars”. Assuming that a liar always lies and someone who is not a liar always tells the truth, which of the following statements is true?

Epimenides is a liar.

Epimenides is not a liar.

It is indeterminable whether Epimenides is a liar or not.

Recall the island Texel with its inhabitants: Knights (who always tell the truth), Knaves (who always lie) and Normals (who sometimes lie and sometimes tell the truth). On this island, a man and a woman may only marry in case they are both Normal, or one of them is a Knight and the other one is a Knave. Now you meet Mr. and Mrs. A who tell you the following:

Mr. A: “My wife is not normal”

Mrs. A: “My husband is not normal”

What types of persons are Mr. and Mrs. A?

They are both Normal.

Mr. A is a Knight and Mrs. A is a Knave.

Mr. A is a Knave and Mrs. A is a Knight.

Indeterminable