# Thread: Mean and variance of random variable distribution function F(z)

1. ## Mean and variance of random variable distribution function F(z)

How do you find mean and variance of a random variable distribution function, F(z) and can someone give an example of this? Thanks.

2. Originally Posted by noles2188
How do you find mean and variance of a random variable distribution function, F(z) and can someone give an example of this? Thanks.
The pdf is f(z) = dF/dz and from the pdf you get the mean and variance in the usal way.

3. I found the mean. How can I find the variance with this number?

4. Originally Posted by noles2188
I found the mean. How can I find the variance with this number?
You should know:

1. $Var(X) = E(X^2) - [E(X)]^2$

2. How to calculate each of the above terms using a pdf.