Hello! :)
If you know the probability of an event occurring, it is easy to compute the probability that the event does not occur. If P(A) is the probability of Event A, then 1 - P(A) is the probability that the event does not occur.
So, it will be 1 - 3/8 = 5/8
5/8 or 62.5% of the probability of the event won’t occur.
Hope you understand and I hope I answered in time!
Good luck!
~ Destiny ^_^