anyways, i'll try to solve it using our way..
Chebyshev's Inequality. If X is a random variable such that Var X exists, then for all r>0,
you want to estimate .
using what you got, E[X] = 0, Var X = 4/3
you need so that
(well, it is just the same.. Ü)
the exact part is:
----- i haven't solved it..