Interpolate off a standard curve in Excel

Most simple thing to do on paper, but somehow near impossible to work out in Excel.

I need to interpolate off a standard curve in Excel.

I have a standard curve and need to find an unknown concentration of a known absorbance.

Just like this; http://class.fst.ohio-state.edu/fst601/Lectures/spectt/Image161.gif

My lecturer would not give us any more hints than to either use the, linear regression equation (which i think i worked out but couldn't get it to calculate the concentration) or use the point finding/picking option (no idea what this could mean)

If anyone could help 开发者_开发问答me out with this I would really appreciate it, and so would my whole class!

In excel, you can do it two ways:

Method 1: Use a standard interpolation/extrapolation formula. (Bingle)

Method 2: Plot any existing data points that you have as an x-y(scatter) plot. Right-click on the data line in the chart and choose 'Add trendline'. Excel will calculate a best-fit line for your data (using linear regression) and display the line over the top of your existing data. If you right-click on this trendline, you can adjust its settings and display properties of it, including the equation used to draw it. Once you have that equation, you can plug in any value of x and get the corresponding value of y.