Hi,

I'm trying to improve myself in solving problems about probabilities and mathematical

expectation, but I find most of problems hard to me especially those problems where

I need to find the expected value, because I feel that every problem needs a way

to think about that is different from the other problems, and trying to apply

the formal definition of the expected value is always useless.

So, could you please provide me with a way to improve myself or some stuff to study from ?