If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

John, Jack and Jill are in a desert. John doesn't like Jill and hence decides to murder him. He poisons the water supply of Jill. Since it is a desert area, Jill must drink or he will die of thirst.

Jack does not know of the actions of John and also decides to murder Jill. To succeed in his ill motives, he removes the water supply of Jill so he dies of thirst.

Jill dies due to thirst. Who murdered Jill?

I throw two dice simultaneously.

What is the probability of getting a sum as 9 of the two numbers shown?

Count the number of triangles in the picture below:

What is the centre of gravity?

What work can one never finish?

A boy purchased a book from a bookkeeper and gave him $100.
The cost of the book is $50 but the bookkeeper has no change, so he gets the change from the next shop and returns the boy his $50.

After some time the next shopkeeper came with the $100 note and told the bookkeeper that the note was a fraud, so he took the money back.

How much loss did the bookkeeper face?

Below toothpicks/matchsticks indicate the group of fishes moving from west to east direction. Can you make them move from east to west by just moving three toothpicks/matchsticks?

There is one thing that goes round the house and also inside the house but never even share a brief touch. What is it?

Before Mount Everest was discovered, what was the highest mountain in the world?