1. ## finding the p.m.f

Let the pmf of X be defined by f(x)=6/((pi^2)(x^2)), x=1,2,3....

show that E(X) does not exist (Can you show that f(x) is a p.mf.?)

And I know that x^-2 converges to Pi^2/6 ..

2. Originally Posted by calculuskid1
Let the pmf of X be defined by f(x)=6/((pi^2)(x^2)), x=1,2,3....

show that E(X) does not exist (Can you show that f(x) is a p.mf.?)

And I know that x^-2 converges to Pi^2/6 ..
$\displaystyle E(X) = \sum_{x = 1}^{+\infty} x f(x)$. Does this series converge ....?

3. Originally Posted by calculuskid1
Let the pmf of X be defined by f(x)=6/((pi^2)(x^2)), x=1,2,3....

show that E(X) does not exist (Can you show that f(x) is a p.mf.?)

And I know that x^-2 converges to Pi^2/6 ..
I assume you mean the sum converges to $\pi^2/6$