What is the definition of expected outcome?

Answer 1

The expected outcome of an experiment, where the outcomes have discrete values, is the sum of the values of each outcome multiplied by the probability of that value occurring.

For continuous variables, it is the integral of each value multiplied by the probability of that value being attained.

The expected value for a variable is the [arithmetic] mean for that variable.

Note, though, that the arithmetic mean may be unrealisable. For example, the expected value for the roll of a fair die is

1*(1/6) + 2*(1/6) + 3*(1/6) + 4*(1/6) + 5*(1/6) + 6*(1/6) = 21/6 = 31/2. And no matter how hard you try, you will not roll 31/2! What the expected value says is that, if you roll the die many times, the average of all the values that you get will be approximately 31/2.