Exponential Trendline and Equation dont match

[Janej]

Hi there

I have a graph of output values that I have to plot linear and exponential trendlines on and then show the equations and calculate for each. The linear equation marries with the line but the exponential one does not. Previous advice has said don't use a line graph, use an x y scattergraph and show the equation fully. I have done both but am still getting the same problem. Can anyone advise

y = 204.278300127163000000000000000000e-0.063574351995067200000000000000x
R2 = 0.795237280846142000000000000000

x=28

shortened equation is:

y = 204.28e-0.0636x
R2 = 0.7952

The trendline at period 28 on the graph is showing about 48, and for me this calc is coming out around 202. I don't have a cle about stats and am doing this for a coursework assignment

Thanks in advance

J
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[shg]

=204.28 * EXP(-0.0636 * x) returns ~34.4 for x=28