Since you revealed the solution, I'm gonna do the next one, OK? (Don't worry, it's quite easy)
4 missionaires travel around the rural parts of Africa. They encounter a cannibal tribe which takes them captive. They plead for their live, begging at the knees of the tribe master. He agrees, but there's a catch: They have to play the game of their lives. They get either a red or a green hat and they have to guess their hat color. There are 2 green and 2 red hats.
They are positioned like this.
X-> | <-X <-X <-X
The " | " is a wall, and the arrows indicate the direction they look. Who has a 100% chance of surviving? (with explanation)