i'm studying for a statistics exam and i dont understand why the mean is sometimes an expectation but sometimes it isnt.
can some one explain me what is the difference?

Question

i'm studying for a statistics exam and i dont understand why the mean is sometimes an expectation but sometimes it isnt. 
can some one explain me what is the difference?

amistre64 · Answer

how do we define the most expected outcome?

amistre64 · Answer

it has something to do with central tendencies right?

anonymous · Answer

i'm really new in statistics so i have no idea what central tendencies mean....
i just know that in some exercises they call the mean same as expectancy but  dont calculate it the same way