Reverse continuous compound interest formula (solve for r)?
By Emily Wilson •
The continuous compound interest formula is pretty simple:
$$ A = P*e^{rt} $$
But how can I solve for $r$?
Wolfram|Alpha introduces this variable $n$ out of thin air, plus imaginary $i$ which I'm not sure is necessary or not if we can add a few more constraints.
Basically, I've got a final amount $A$, an initial principal $P$, an amount of time $t$ and I want to know what the equivalent interest rate is, assuming it was compounded. If "continuous" is too hard to solve for, monthly would also be fine.
$\endgroup$ 31 Answer
$\begingroup$$\frac{A}{P}=e^{rt}$
so $\ln(\frac{A}{P})=rt$ which should be easily solved for $r$
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