Question about charts

  • Thread starter Thread starter Marc
  • Start date Start date
M

Marc

If I have two lines in a line graph and they criss-cross
(like a supply and demand curve), how can I find the exact
values on the x and y axis where the two lines cross? Is
this possible by using Excel?
 
Let's hope you made XY chats (no Line charts) - change chart if necessary
Insert Trendlines for both (better yet use SLOPE and INTERCEPT functions)
So Now you know y1=m1x1+b1 and y2=m2x2+b2
At point of intersection y1=y2 and x1=x2
m2x+b2 = m1x+b1
x= (b1-b2)/(m2-m1)
y = m1x + b
Its all rather simple algebra.
Bernard (you can call me Prof <grin>)
www.stfx.ca/people/bliengme
 
[This followup was posted to microsoft.public.excel.charting and a copy
was sent to the cited author.]

If you know the equations of the two lines, solve the problem
algebriacally.

If you don't, solve it by 'trial and error' or an iterative process.
Plot both series. Change the min./max. values of the x- and y-axis to
'zoom in' on the intersection point.

You might find it useful to use the 'Interactive Display' add-in
available from my site to iteratively converge on the intersection.

--
Regards,

Tushar Mehta
MS MVP Excel 2000-2003
www.tushar-mehta.com
Excel, PowerPoint, and VBA tutorials and add-ins
Custom Productivity Solutions leveraging MS Office
 
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