You randomly choose one coin from the bag and flip it four times. What is the percent probability of getting four heads? So let's think about it. When we put our hand in the bag and we take one of the coins out, there's some probability that we get an unfair coin. And three of the four coins are unfair. So there's a 3 4 probability that we get an unfair coin. And then there is only one out of the four coins that's fair.