What occurs twice in a week, once in a year but never in a day?

A train leaves from point A for point B at 80 mph. After half an hour, another train leaves from point B for point A at 60 mph.

Which of the trains will be farther from point A when they meet ?

A man stands on one side of a river, his dog on the other. The man calls his dog, who immediately crosses the river without getting wet and without using a bridge or a boat. How did the dog do it?

A pond had 60 fish, out of which, all but 20 died.
How many fishes are now present in that pond?

You walk into a room where there are three primates held in their respective cages:
1) A lion who is eating the flesh of a goat.
2) An orangutan who is playing with blocks.
3) A donkey who is sitting idle.

Who is the most intelligent primate in the room?

A deaf and mute man goes to the train station. Tickets for the train are 50 cents each. The man goes to the ticket booth and hands the man inside just a dollar. The man in the booth hands him two tickets.

How did the man in the booth know to give him two tickets without even looking at him?

John is asked to stand behind Jacob and Jacob is asked to stand behind John. Both of them feel confused about it and don't know what to do?

But it is quite possible, do you know how?

Irene killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

That attorney is my brother, testified the accountant.

But the attorney testified he didn't have a brother.

Who is lying?

John named his first son Alpha, second Beta, third Charlie and fourth Delta. What is the fifth son's name?