Thanks guys.

A quick background. I get a trendline and select the exponential function.
It comes up with a formular i.e.
y = 3949.4 e "superscript" 0.012x
I have the y number = 10,000
I used your formular
Log (10,000/3949.4)/0.012 and get the number of 35.08, however, I understand
I shall get a number close to 80. Am I putting the wrong formular?

Thanks
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"joeu2004" wrote:

On Nov 29, 6:27 am, K Lee wrote:
Can you help me to solve the below equation in excel ?
Y= 3494e0.012x and Y=10,000, therefore,
10000=3949e0.012x,
I like to find out the value of x

I wonder if "e" is the mathematical constant (aka Euler's number), and
you meant to write:

Y = 3494*e^(0.012*x)

In that case, we really should require that you complete the algebraic
transformation yourself, but what the heck ....

ln(Y / 3494) = 0.012 * x

x = ln(Y / 3494) / 0.012

In Excel, if Y (10000) is in A1, in A2 you would write the formula:

=ln(A1 / 3494) / 0.012

As a double-check, in A3 you might write:

=3494 * exp(1) ^ (0.012 * A2)

We expect __about__ 10000. The result might not be exact because of
the many approximations and the artifacts of binary computer
arithmetic.