1. ## standard normal formula

Hi;
I know the formula is Z = (X - mean)/standard deviation,What I don't know
is how do I know when I convert a normal distribution into z
which is written as X ~ N(mean,variance or standard deviation).

How do I know if X ~ N(50,4) the number 4 is variance or standard deviation
because when I put it back into the Z formula it has to be divided by standard deviation?

Thanks.

2. ## Re: standard normal formula

I thought it was always written as X ~ N( Mean , Standard Deviation )...

3. ## Re: standard normal formula

The notation people use varies so you'll have to check elsewhere in their work for the system they are using.