P stands for for probabiltiy for each number 4, 6, 8 computr the mean and the expected value

The mean and the expected value are pretty much the same thing. So all you do is multiply each number by its probabilitdamned then add:

4 * .1 + 6 * .6 + 8 * .3 = 6.4. (Hopefully this is right, I'm just learning it myself, currently...)