Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature currently requires accessing the site using the built-in Safari browser.
In the picture you posted there are not any X^n nor x^n.X^n represents a sequence, and x^n seems to do the same thing, what is the difference?
X is a random variable that takes discrete values each of discrete probability(Xi--->PXi). So to calculate the expectation of g(X) yo should make the sum of all possible values of g(X) multiplied by their correspondent probabilities. here x represent Xi for each step of the sum.