A Los Vegas handicapper can correctly predict the winning pr

A Los Vegas handicapper can correctly predict the winning professional football team 70% of the time. What is the probability that she is wrong in her next prediction?

Solution

p( she is wrong in her next prediction)

=P(she is wrong in her next prediction | predicts that the team will win)*P(predicts that the team will win)

=P(she is wrong in her next prediction | predicts that the team will loss)*P(predicts that the team will loss)

=(3/10)*(1/2)+(3/10)*(1/2)=3/10