Suppose that two players are playing a game, players select between two choices:
Scenario 1:
player $1$ chooses option $1$ with probability $60\%$, option $2$ with $40\%$
player $2$ chooses option $1$ with probability $40\%$, option $2$ with $60\%$
Scenario 2:
player $1$ chooses option $1$ with probability $50\%$, option $2$ with $50\%$
player $2$ chooses option $1$ with probability $50\%$, option $2$ with $50\%$
question: which scenario are both players most likely to choose the same option if the game is played repeatedly over several stages?
Intuitively, scenario $2$ would be the scenario for which both players are most likely to choose the same option, but how do I formally prove my intuition?
Scenario 1
Probability that player $1$ chooses option $1$ and player $2$ chooses option $1$:
$0.6*0.4 = 0.24$
Probability that player $1$ chooses option $2$ and player $2$ chooses option $2$:
$0.4*0.6 = 0.24$
Probability that at least one of these (mutually exclusive) events happens is their union:
$0.24+0.24 = 0.48$
Scenario 2
Probability that player $1$ chooses option $1$ and player $2$ chooses option $1$:
$0.5*0.5 = 0.25$
Probability that player $1$ chooses option $2$ and player $2$ chooses option $2$:
$0.5*0.5 = 0.25$
Probability that at least one of these (mutually exclusive) events happens is their union:
$0.25+0.25 = 0.50$
$0.50 > 0.48$, so both players have a higher probability of choosing the same option in scenario 2.