Does the dark vader rule work if 0 isnt included in the domain?

i.e. f(x)=2y^-3, y>1. The policy has a limit of 25. Need to find expected value.



F(x)= 1-x^-2, S(x)= x^-2. => -1/x |25, 1 = 24/25.



the correct answer is 49/25.



can someone explain to me what I am doing wrong please?

Does the dark vader rule work if 0 isnt included in the domain?