this is a permutation question. the number of possible arrangments you have for the remaining 4 events, are . only one of these arrangements are correct. thus the probability of you choosing that arrangement is

one way to think of the permutation is to say, you have 4 choices for the event in the second position, for each of those, you have three choices for the third position, for each of those, two choices for the fourth position and one choice for the 5th. in all, that is 4*3*2*1 = 4! choices