Please be detailed and specific to answer this question by giving examples and arguments.

Much of probability theory may seem to be computation, with discrete and continuous random variables, for example, but these computations all rely on a more basic structure involving sets. Describe this basic structure, and give an example using random variables, pointing out how the basic elements of the theory appear in a computation. (Since the notion of random variable is itself part of the basic structure, you will have to say carefully what it is before you give your example)