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