Reading data from a graph

[Mnylen]

I have a set of data that I have plotted in a graph. I have about 10-15 data points, the graph has couple of bends in it which I am very keen to preserve. I need to be able to identify y-values corresponding to x-values between my known data points. Is there any smart way in Excel to handle this?

I have tried looking at functions like "logest", "linest", "growth", "trend", etc but none of them seem to be doing what I need.

The back-stop would be to do it the old fashioned way and print out the graph and then use a ruler. Feels a little bit inexact and stoneage...

Thank you in advance

 

[MarkCBB]

can you give me a sample of your data?

 

[Mnylen]

Here you are:

Temperature %wt
15 1
95 7.26
149 15.79
175 20.06
232 30.02
342 54.08
369 59.44
509 83.01
550 87.21
585 90.11