interpolating y value on a scatter graph

Good Day

I have scatter in sheet "Graph" and would like to interpolate y (invert) based on x (chainage) ied n sheet "roads". The x and y for the scatter concern are from sheet 1 column c and column (x). I have copied x and y into sheet 3 and tried linest, forecast and it is not giving the desired outcome. I tried using one of the x's in the array to see if it will return y, ie x=50, y=1752.38. See attached


You assistance will be appreciated

Hello Justmcd
My maths isnt bad but Ive never been brilliant with graphs unless they are very basic. Ive had a look and I (sort of) understand what interpolation is.
I also read that Excel doesn't have an Interpolation function but they also explained how to create one (probably using the UDF route).

Take a look at this link and see if its any help. Let me know how you get on.

http://www.blueleafsoftware.com/Products/Dagra/LinearInterpolationExcel.php

HTH

Hercules

Hi Hercules

Thanks a lot with the link. It works like a charm.

Justmcd

Thats great, and your welcome.
Thanks for letting me know.