Standard deviation

[patiencescientist]

I need to chart standard deviation in my worksheet. There needs to be 3
times the standard deviation (positive and negative) Is the average added to
these two values
to be correct thanks in advance.

 

[Bernard Liengme]

This show how to add the lines
http://peltiertech.com/Excel/Charts/AddLineHorzSeries.html

You need three lines
=Average(rng)+3*stdev(rng)
=Average(rng)
=Average(rng)-3*stdev(rng)

best wishes

 

[David Biddulph]

What is correct depends on what you are trying to show.