‘…for each x in the range of the random variable X, we have
p(x) = P(X = x)
… an upper-case letter… is used for the label of a random variable, while the corresponding lower-case letter (x) is used as representative of the possible values the random variable might take.’
(from my textbook, published by the Open University)
There comes a time in any mathematics course that I feel like Mr. Bean in the exam. What once made sense becomes unintelligible gobbledegook. This is when I stop and take a break.