There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?

Distances from you to certain cities are written below.

BERLIN 200 miles

PARIS 300 miles

ROME 400 milesAMSTERDAM 300 miles

CARDIFF ??? miles

How far should it be to Cardiff ?

John is the son of Jacob.
So,
Jacob is the_____of John's father?

A mad serial killer kidnaps people and forces them to play the game of 2 pills with them, In this game, there are pills in the table and one of them is normal pill while the other one is deadly poisonous.
The victim will choose one pill and the killer will pick the other pill and both simultaneously will swallow the pill with water.
victim dies every time.

One day the serial killer kidnaps the Joseph and forces him to play the same game with him.

Joseph solves the mystery of the two pills and remains alive.

Explain?

How can you make the following equation true by drawing only one straight line: 5+5+5=550 ?

I throw two dice simultaneously.

What is the probability of getting a sum as 9 of the two numbers shown?

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

An infinite number of mathematicians are standing behind a bar. The first asks the barman for half a pint of beer, the second for a quarter pint, the third an eighth, and so on. How many pints of beer will the barman need to fulfill all mathematicians' wishes?

A plane crashed between the border of Mexico and America. Where do you bury the survivors?

I make a loud sound when I’m changing. When I do change, I get bigger but weigh less. What am I?