Why is a river so rich ?

The host of a game show, offers the guest a choice of three doors. Behind one is a expensive car, but behind the other two are goats.
After you have chosen one door, he reveals one of the other two doors behind which is a goat (he wouldn't reveal a car).

Now he gives you the chance to switch to the other unrevealed door or stay at your initial choice. You will then get what is behind that door.

You cannot hear the goats from behind the doors, or in any way know which door has the prize.

Should you stay, or switch, or doesn't it matter?

What is the centre of gravity?

John’s parents have three sons: Snap, Crackle, and what’s the name of the third son?

Which city is three-fifths chick two third cat and 50% goat?

Which is the correct shadow of the bird?

Can you find out the remainder when 3^300 is divided by 5?

There’s a one-story house in which everything is yellow. Yellow walls, yellow doors, yellow furniture. What colour are the stairs?

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

A large container is kept in open under the rain. Every passing hour, the water collected inside the container becomes double what it was.

In ten hours, the container is filled completely. Can you calculate how long would it have taken to be filled in half?