Finding unknown X value from known Y value from curve of best fit

Dear all, I am a novice when it comes to escel, I have managed to draw a line graph containing a line of best curve. I now need to find many 'unknown' y values, by putting in the known x axis coordinates. The formula that excel has put in my chart is this: y = 12.405e0.1162x. I dont know what do with it!
I have attached the file and would be grateful if somebody can help.

Thank you

1st note, title indicates you are trying to solve for x at a given y, text of post indicates you are trying to solve for y at given x. Not a big deal, because a little algebra makes both questions essentially the same in this case.

1st, and maybe most difficult of this problem is getting the coefficients from the trendline into the spreadsheet. Easiest might be to hand enter the values into the spreadsheet (probably want to format the chart trendline to show all digits so you don't run into other problems). If this is something you will be doing regularly, you should probably work on learning how to use the LINEST function to do the regression directly in the spreadsheet.

Once the coefficients are in the spreadsheet, getting y at known x is as simple as entering the values and function into appropriate cells. If you are trying to get x at known y, then a little algebra should allow you to rearrange the equation, and then that function can be entered into a spreadsheet.

Sorry I actually meant finding unknown y from known x. I wont be doing this regularly and really havent got the time to learn anything in depth. I dont even know how to get the coefficients of the trendline, this is all Greek to me, I just want to enter x and get y!!!! sorry

this is all Greek to me

I can appreciate this. I certainly find that, the better I understand the problem (and the math behind the problem), the easier it is to program the solution into Excel.

With that in mind, I think that we need to ascertain what you know and don't know in order to best help you come up with a final solution. With that in mind, here is a basic approach to getting the solution. Review it and specify where in this process you are getting stuck:

1) Enter data into spreadsheet
2) Plot data on an XY/Scatter plot.
3) Tell Scatter plot to generate trendline based on data and show the trendline equation on the chart.
4) Enter trendline parameters into spreadsheet.
5) Enter desired X value and a formula that will calculate the desired Y value into the spreadsheet.

Explain where you are stuck and why you are stuck, and we should be able to help you figure out how to get the desired information from Excel.

Guys thank you so much for the help, my colleague managed to solve my problem last night,
'e' was a constant , and = 2.71828182845904
I just had to write the following formula and put in x to find corresponding y
=12.405*(POWER(2.71828182845904,0.1162*11))

FWIW, Excel (and every other spreadsheet and programming language) have e hard coded into them. In Excel, you can use the =EXP() function to get powers of e: =EXP(0.1162*11).