There are many ways to calculate the expected value. I covered one approach in a previous blog. You can also multiple your X value by the corresponding probability. So suppose you were given the following:
And you wanted the expected value of X you would obtain E(X)=1*.20+2*.40+3*.40= 0.20+0.8+1.2=2.2 . It depends on your probability distribution. There are several equations depending on the scenario.
-Mooore to follow- Amy