[faith]

Do anyone know how to determine the area under the curve using excel 2007? What is the best method to use and how to apply it on excel if given x and y values?

[Arkcon]

That would really depend how you've gotten a curve into Excel.  I suppose if it's a table of values, you can use the trapezoid rule to estimate the area under a parabolic curve, see this web page:  http://people.stfx.ca/bliengme/ExcelTips/AreaUnderCurve.htm

If you've managed a quadratic fit to the curve, I suppose you could take it's integral.   This isn't HPLC data, again, is it?  Because, like I told you before, no one does it this way, any more.

[faith]

Thanks for the reply, the information was useful. I decided to use the trapeziod method in determining the area under the curve and this is my result



x   y= f(x)   area   
3.00   1.17      
3.60   1.02   0.66   
4.00   0.90   0.38   
4.70   0.63   0.54   
5.50   0.59   0.49   
6.25   0.63   0.46   
7.00   0.66   0.48   
7.50   0.79   0.36   
8.60   1.20   1.09   
9.00   1.45   0.53
9.40   1.65   0.62
10.00   2.05   1.11
10.45   2.26   0.97
10.85   2.62   0.98
11.25   3.00   1.12
   Area   9.79
the method used is trapezoidal approximation      
to calculate the area increament by       
(d8+d9)/2 * (c9 - c8).      

but my question how would l plot a graph that would look like a curve. I went to chart wizard and clicked on area and column to plot a curve graph, but it did not give me what l needed. I even tried to join the two graph together, but all l get was just one graph. Moreover, l used the Visual basic editing on the tool bar, but my function keeps giving me errors. I know l am doing something wrong, which l cant't figure out.
Is there any clue to what l did wrong,thanks

[Borek]

Scatter plot?

[Arkcon]

Click around on your resulting plot.  If you don't like an axis, or the curve, you may be able to change it from there, or point the curve to different data points of your spreadsheet. It's a good way to learn.