Check out our Excel Charting Resources | ||||

Back to Charting for Excel archive index

Back to archive home

## Area under a curve

Posted by Chad Pearson on December 31, 2001 1:18 PM

## My Calculus may be rusty

Posted by Adam S. on December 31, 2001 3:12 PM

Back to archive home

Hello

I was wondering if anyone can tell me how to determine

the area under a curve plotted in an XY scatter plot or

Area plot.

Thanks

I was wondering if anyone can tell me how to determine

the area under a curve plotted in an XY scatter plot or

Area plot.

Thanks

Well, If you have an equations (I'm assuming based on a trendline) you're almost there.

I believe you just need the integral of that equation, then plug whatever x you need.

Example I. Simple example (line equation y=4)

x y

0 4

1 4

2 4

3 4

the Integral of y=4 with respect to x is: Area = 4x/1 (or just =4x)

so the area under the line at x=4 = 4*(4) =16

Example II: straight diagnol line (y=x)

x y

0 0

1 1

2 2

3 3

Integral of y=x: Area = (x^2)/2

so at x=4, [(4)^2]/2 = (16)/2 = 8 ..sounds good so far

Example 3; a Curve equation: y=(x^2) + 3x + 1

x y

0 1

1 5

2 11

3 19

Integral: Area = [(x^3)/3] + [3(x^2)/2] + x

so at x=4, the area under the curve is equal to:

[(4^3)/3] + [3*(4^2)/2] + 4 simplified to

[(64/3) + (3*16/2) + 4] simplified to

21 + 24 + 4 =49

Feel free to tell me if I'm off a bit somewhere..it's been awhile.

Hope that helps out somewhat,

Adam S.

This archive is from the original message board at www.MrExcel.com.

All contents © 1998-2004 MrExcel.com.

Visit our online store to buy searchable CD's with thousands of VBA and Excel answers.

Microsoft Excel is a registered trademark of the Microsoft Corporation.

MrExcel is a registered trademark of Tickling Keys, Inc.

All contents © 1998-2004 MrExcel.com.

Visit our online store to buy searchable CD's with thousands of VBA and Excel answers.

Microsoft Excel is a registered trademark of the Microsoft Corporation.

MrExcel is a registered trademark of Tickling Keys, Inc.