It sounds as though you need to interpolate between the two data points on
either side of your unkknown point.
Are you looking for an X to go with a known Y or a Y to go with a known X

"brendas182" wrote:

I'm trying to find an unknown data point (X) by using a set of standards (two
sets of data, an X and Y)that have been made into a line graph. Usually I do
this manually by graphing the line and printing out a large version and just
giving a best estimate to where the point would be. The closest thing I can
find that functions in this way is a trendline, but the point found needs to
actually be on the line itself, not the trendline. I was wondering if any of
you know how to do this using excel because I can't seem to figure it out.
Thank you!