A chemist weighed an object and found its mass to be 250 grams. The objects actual mass is 360 grams. What was the chemists percent of error?

Let x have probability generating function gx (s) and let un generating function u(s) of the sequence uo, u1, satisfies p(x > n). show that the (1- s)u(s) = 1 - gx(s), whenever the series defining these generating functions converge.