Is there a symbol for average?

Answer 1

Sometimes it is denoted by putting a line above the variable that is being averaged. The "Expectation value" of a random variable - is like a weighted average. I'll explain by way of example: lets say X represents your grades in high school and how much weight should be given to each grade (not all courses are equal). X is a random variable.

E[X] or <X> or the Greek letter mu (µ) - are a few of the common symbols for the Expected Value of X - or your weighted average of high school grades.