A game is considered "fair" if the player can expect to win $0. Which is a fair game?
A Game A
cost to play: $1
prize: $5
probability of winning: 0.2
Game C
cost to play: $3
prize: $20
probability of winning: 0.1
B Game B
cost to play: $2
prize: $10
probability of winning: 0.3
Game D
cost to play: $4
prize: $10
probability of winning: 0.5

Asays "we are both knaves" and b says nothing. exercises 24–31 relate to inhabitants of an island on which there are three kinds of people: knights who always tell the truth, knaves who always lie, and spies (called normals by smullyan [sm78]) who can either lie or tell the truth. you encounter three people, a, b, and c. you know one of these people is a knight, one is a knave, and one is a spy. each of the three people knows the type of person each of other two is. for each of these situations, if possible, determine whether there is a unique solution and determine who the knave, knight, and spy are. when there is no unique solution, list all possible solutions or state that there are no solutions. 24. a says "c is the knave," b says, "a is the knight," and c says "i am the spy."