Find the missing letter in the last circle logically in the given below picture.

You are trapped in a room with two doors. One leads to certain death and the other leads to freedom. You don't know which is which.
There are two robots guarding the doors. They will let you choose one door but upon doing so you must go through it.
You can, however, ask one robot one question. The problem is one robot always tells the truth, the other always lies and you don't know which is which.
What is the question you ask?

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

O T T F F S S ?

Prove that the below maths equation is true.

8 + 8 = 91

I have a hole in my back and legs I lack.
I live where I can’t breathe and I eat without teeth.
What am I?

There was once a college that offered a class on probability applied to the real world. The class was relatively easy, but there was a catch. There were no homework assignments or tests, but there was a final exam that would have only one question on it. When everyone received the test paper it was a blank sheet of paper with a solitary question on it: 'What is the risk?'.Most students were able to pass, but only one student received 100% for the class! Even stranger was that he only wrote down one word!
What did he write?

In a boat, the father of a sailor's son is sitting with the son of the sailor. However, the sailor is not present on the boat.

Can this even be possible?

I’m tall when I’m young, and I’m short when I’m old. What am I?

If there are fifteen crows on a fence and the farmer shoots a third of them, how many crows are left?

Given that

(78)^9 = 6
And (69)^4 = 11

Can you find out

(99)^2 =?

(Note: This is Logical, not Mathematical)