Let (X,Y)(X, Y)(X,Y) be uniformly distributed on the triangle 0≤x≤1,0≤y≤x0 \le x \le 1, 0 \le y \le x0≤x≤1,0≤y≤x. What is E[Y∣X=0.5]E[Y | X = 0.5]E[Y∣X=0.5]?
0.250.250.25
0.50.50.5
0.750.750.75
1/31/31/3