Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

On a magical land of Mexico , all the animal in the land are rational.

There are 10 tigers and one goat.
Tiger can eat goat but since it's a magical land , the tiger who eats the goat , turns into goat and then can be eaten by the remaining tiger(s).

If we leave them for some time then how many goat and tiger will be there , when we come back ?

Why are all black people so quick ?

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

A bag contains 64 balls of eight different colours. There are eight of each colour (including red). What is the least number you would have to pick, without looking, to be sure of selecting 3 red balls?

You have to fill the below given grid in a manner that every row and column contains the digits 1 to 6. Also, make sure that the squares that are connected with each other must contains the same digit.

You board a train. The train will have to enter a tunnel soon. You are claustrophobic. Which place is the best for you to sit?

What kind of tree can you carry in your hand?

What goes through cities and fields, but never moves?

What happened when the wheel was invented?