Determining line values on a chart

[Half Measures]

Is there a way to determine a Y coordinate on a Scatter with Straight Lines and Markers chart, given a specific X value? For instance, a line is drawn connecting points on said chart type. If I have a predetermined X value, is there an expression used to give the exact Y value from that line that corresponds with that given X value on the chart?

 

[JLGWhiz]

Wouldn't it just be whatever your plot formula is ? Y = 2X, etc.

 

[Half Measures]

Wouldn't it just be whatever your plot formula is ? Y = 2X, etc.

To be more specific, let's say I've created points on the chart. Those points will be connected with a line. What if I am wanting to know the Y coordinates on that line between those two points, if only given an X value? Does that make better sense? It's hard to explain in text only. Wish I could do a share-screen call with you, to show you what I'm talking about better.

I mean, I can see where if I hover my cursor over a point on a chart, it will give me the X and Y coordinates. But, those have been calculated already. I am wanting the coordinates on a line between two points, if given a value for X. If that X value hasn't been calculated using the points, I would like to know the values on the line.

 

[JLGWhiz]

If I recall correctly form my geometry class some 65 or so years ago, you find the Y value of an X cordinate by using the formula for the plot slope and solving for Y when you have the value of X. But that was long ago and I could be wrong. Now If you are plotting strictly from a range of values on a worksheet range and have no idea where the numbers in that range came from, that could be a problem. You would have to reverse engineer to get the formula that gives you the relationship of X to Y. That could be very difficult with a scatter chart because they are not created with linear equations. Sorry I cannot help you more, but you need to know the equation used to produce the chart to be able to detrmine the Y value when X value is known.

 

[Half Measures]

If I recall correctly form my geometry class some 65 or so years ago, you find the Y value of an X cordinate by using the formula for the plot slope and solving for Y when you have the value of X. But that was long ago and I could be wrong. Now If you are plotting strictly from a range of values on a worksheet range and have no idea where the numbers in that range came from, that could be a problem. You would have to reverse engineer to get the formula that gives you the relationship of X to Y. That could be very difficult with a scatter chart because they are not created with linear equations. Sorry I cannot help you more, but you need to know the equation used to produce the chart to be able to detrmine the Y value when X value is known.

Thank you for the response. Guess I was trying to find a quick, easier way of doing this. lol. Going to take a deeper dive, unfortunately. Guess I was confused how the linear chart works. Didn't know that was done from equations. I thought it was more of a trendline, trying it's best to connect dots that do not add up to a straight line. Was thinking the same could be done with lines that connect dots, in finding coordinates on lines that haven't any calculated points made. I suppose the lines on the scatter plot charts I'm talking about have lines for aesthetic purposes, not equational ones.