The trendline is different from the curve

Hello all,

I have a set of data and I made a graph out of it, I was looking to find the value of x when y is let's suppose 1000, The values in the data set are somewhat nearer to 1000 but I would like to find the exact value of x when y is at 1000, I have tried using a trendline but the trendline curve and my graph curve is not in the same line, the trendline I used is logarithmic that was the only trendline that was somewhat nearer to my curve, is there any other way to find the exact values of x or y when we know any one of them. could someone please help me with the problem, I have attached the excel sheet, please find it attached

Thank you for your time and attention.

We cannot diagnose the invisible. Please attach a sample file. Guidance is in the yellow banner (top).

Administrative Note:

Is your forum profile showing the Excel PRODUCT that you need this to work for?

Members will tailor the solutions they offer to the Office PRODUCT (Excel, NOT Windows) that you have. Please check that your forum profile is up-to-date in this respect. If you aren't sure, in Excel go to File | Account and report what it says below the MS logo at the top of that page. If your product is for Mac, please also state this.

The three most recent Excel products are Excel 2019, Excel 2021 and MS365 - if you are using MS365, please give this name along with the version number in your profile (e.g. MS365 Version 2306). This is in the About Excel section further down the Account page.

Thanks.

How much of this is Excel programming and how much is a deeper data analysis question (independent of which programming language you choose to use)?

If you have an algorithm you want to use, help us understand the algorithm and we'll help you program that algorithm into Excel.

If this is a broader data analysis question, then I usually see two broad strategies used for this kind of problem.
1) Regression -- where the analyst determines a suitable mathematical model and regression algorithm, uses the regression algorithm to determine appropriate "best fit" parameters for the model, then solves the problem(s) from there. It appears you have so far limited yourself to the "linear" functions available in the chart trendline feature. If you wish to use a regression type of approach, I think you will need to consider models outside of those available in Excel's chart trendline.
2) Interpolation -- where the analyst assumes that each tabulated point is "exact" and uses a suitable mathematical model (usually a straight line) to estimate what is happening between tabulated data points.

How would you like to proceed?

Which version of Excel are you using? I have asked you to update your profile - please do this NOW.