Let XXX be a discrete variable with P(X=k)=1/4P(X=k) = 1/4P(X=k)=1/4 for k∈{−2,−1,1,2}k \in \{-2, -1, 1, 2\}k∈{−2,−1,1,2}. What is E[X]E[X]E[X]?
-1
0
1
0.5