Good Riddles

Question: A man wants to buy a used car. He finds a beautiful Buick for $9500, but he buys it without paying a dime.

How did he manage this?

Question: There are five hen and rooster pairs. Each pair has one baby every month.

How many chickens will there be in one year?

Question: I stand in one place yet I fill a whole room.
I can be filled with molten rock and come in every hue.

What am I?

Question: Which comes first, chicken or egg?

Question: What single line can you add to the following statement to make it true?

5+5+5=550