Hello all,
Iam an engineering graduate and new to excel. I have a doubt about how to interpolate between curves (polynomial) on charts having a secondary axis.
I have a chart and extracted all the points through "WebPlotDigitizer". it works great.
But how to interpolate. There is an attachment (picture) which depicts the graph. If I consider to interpolate my data for value of 30 on my secondary axis, how to proceed.
Your explanation will be valuable to me. I have tried a a lot , but not with graph having secondary axis tooo...

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