Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

Three people enter a room and have a green or blue hat placed on their heads. They cannot see their own hat but can see the other hats.
The colour of each hat is purely random. They could all be green, blue, or any combination of green and blue.
They need to guess their own hat colour by writing it on a piece of paper, or they can write 'pass'.
They cannot communicate with each other in any way once the game starts. But they can have a strategy meeting before the game.
If at least one of them guesses correctly they win $10,000 each, but if anyone guesses incorrectly they all get nothing.
What is the best strategy?

A man is looking at a photograph of someone. His friend asks who it is. The man replies, “Brothers and sisters, I have none. But that man’s father is my father’s son.” Who was in the photograph?

What number comes next in this sequence:
7 8 5 5 3 4 4 _

I throw two dice simultaneously.

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

I know a ten-letter word in the English language which can be typed using only the top rows of the computer keyboard.

You have a basket containing ten apples. You have ten friends, who each desire an apple. You give each of your friends one apple.
Now all your friends have one apple each, yet there is an apple remaining in the basket.
How?

It's pretty hard to give up.
If you remove a part of it, you will be left with a bit.
Even if you remove another part, the bit still remains.
Remove one more and it still remains.

What is it?

Why did Buffon take the goal with him after every Juventus match?

You and your two friends are working in a multinational company. How can you three find out the average salary of you all without disclosing your own salary to the other two?