How old is your son? asked a man to his neighbour. My son is five times as old as my daughter and my wife is five times as old as my son. I am twice as old as my wife whereas my grandmother, who is celebrating her eighty-first birthday is as old as all of us put together.

How old is the man's son ?

There are people and strange monkeys on this island, and you can not tell who is who (Edit: until you understand what they said - see below). They speak either only the truth or only lies.
Who are the following two guys?
A: B is a lying monkey. I am human.
B: A is telling the truth.

I am sure no one can have two things for dinner. what are they?

Which is faster, Heat or Cold ? Explain.

If you toss a coin 10 times and it lands heads up every time, what are the chances it will land heads up if you toss it again?

The more it dries, the wetter it becomes. Can you tell what it is?

Mr Black, Mr Gray, and Mr White are fighting in a truel. They each get a gun and take turns shooting at each other until only one person is left. Mr Black, who hits his shot 1/3 of the time, gets to shoot first. Mr Gray, who hits his shot 2/3 of the time, gets to shoot next, assuming he is still alive. Mr White, who hits his shot all the time, shoots next, assuming he is also alive. The cycle repeats. If you are Mr Black, where should you shoot first for the highest chance of survival?

Two in a corner, one in a room, zero in a house, but one in a shelter. What is it?

what does the below math rebus puzzle mean?

Eight of us go fourth, not back, to protect our king from an attack. What are we?