How to calculate the probability in the event that a number is not the one from the list?

Question

I have a list:

lst = [10,20,39,50]

How to calculate the probability in Python that a number picked up from the list is not 10? (An event can be supposed)

Answer 1

The probability of getting 10 from the list is just the number of times 10 appears on the list over the length of the list:

p10 = lst.count(10) / len(lst)

Whereas the probability of NOT getting a 10 is just the complement:

p_not10 = 1 - p10