Replace the question mark with the correct number.

You need to arrange three 7 and mathematical symbols to form number 1?

I have two coins.
* One of the coins is a faulty coin having a tail on both sides of it.
* The other coin is a perfect coin (heads on side and tail on other).

I blindfold myself and pick a coin and put the coin on the table. The face of the coin towards the sky is the tail.

What is the probability that another side is also tail?

Solve the following series:
AZ, GT, MN, __, YB

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

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?

Buy me, smell me or deliver me, I do not change.

Who am I?

A person was found dead on a big green land with no trees or buildings around. When the police arrived, they found a piece of rock lying next to him and the man was wearing clothes comprising of red, blue and yellow colours.

Can you tell who the person is and what was the cause of death?

A Scientist was fifty years old in the year 2000 but he was forty years old in the year 2010. How can this be possible?

PS: It has a logical answer.

You knock a Table over in the library, and suddenly 20 eyes are looking at you.