Standard deviation calculation

[Anand]

If I have the mean and a 95% probability value for a distribution, is there a
function that will calculate the standard deviation?

I currently use norminv with a guess for the standard deviation and then
goal seek to get the implied standard deviation. I was wondering if there is
a more straightforward way to calculate the implied standard deviation if I
know the mean and the 95% probability value.

Thanks,

Anand

 

[David Billigmeier]

Use NORMSINV() and some algebra...

=(X-mean)/NORMSINV(your_probability)

Where X is the value you calculated the 95% probability for (normal notation
when calculating a Z score)