Brian Teaser For the Day: Puzzle

Ok for the Logic/mathematicians

1. You've got 27 coins, each of them is 10g, except for 1. The 1 different coin is 9g or 11g (heavier, or lighter by 1g). You should use balance scale that compares what's in the two pans. You can get the answer by just comparing groups of coins.

What is the minimum number weighings that can always guarantee to determine the different coin.

1. WHATCHYA GONNA DO (2 GOATS AND A CAR)
   You are on a game show and there are three doors. The presenter tells you that behind one of doors there is a car and behind the other two are goats. If you pick the car you win it. After you have picked a door the presenter opens a different door with a goat behind it, he then gives you the chance to change what door you open. What should you do?
   Hint: It is not 1/2 as you would first think. ;)

3.SEQUENCE PUZZLE
The below is a number puzzle. It should be read left to right, top to bottom.
Question 1: What is the next two rows of numbers?
Question 2: How was this reached?

   1
  1 1
  2 1
1 2 1 1

1 1 1 2 2 1
? ? ? ? ? ?
? ? ? ? ? ? ? ?