The answer is 165438+8/0. Things can be divided into two situations: he can go out and he can't. It can be calculated that he can't go out with the key, and then 1 reduces the probability of not going out. There are five in the total event 1 1, but five of the nine fake keys were selected when you were not going out, so C9' 5 divided by C 1 1' 5 is equal to 1+3/0,/kloc.