If Rajina's daughter is my daughter's mom, who am I to Rajina?

I am the beginning of the end, and the end of time and space. I am essential to creation, and I surround every place. What am I?

People are waiting in line to board a 100-seat aeroplane. Steve is the first person in the line. He gets on the plane but suddenly can't remember what his seat number is, so he picks a seat at random. After that, each person who gets on the plane sits in their assigned seat if it's available, otherwise, they will choose an open seat at random to sit in. The flight is full and you are last in line. What is the probability that you get to sit in your assigned seat?

When my father was 31 I was 8. Now he is twice as old as me. How old am I?

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?

There is so small cabin inside a deep forest.
All the forest burned out to worst possible but the inside of the cabin is still the same.
However all the person inside the cabin die.

How come ?

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

We have shown you a regular water barrel as below. Without using any measuring device can you check if the barrel is more than half-filled or less than half-filled?

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

Can you arrange four 9's and use at most 2 math symbols, to make the total 100?