Answer
$ r\approx 9.35\%$
Work Step by Step
The amount A after t years due to a principal P
invested at an annual interest rate r, expressed as a decimal,
compounded n times per year is $A=P\displaystyle \cdot\left(1+\frac{r}{n}\right)^{nt}$
---
$t= 3$ years,
$n=1$ (annually)$,\quad nt=3$
$A=850,000$
$P=650,000$
$r=?$
$850,000=650,000(1+\displaystyle \frac{r}{1})^{3}\qquad.../\div 650,000$
$1.3077=(1+r)^{3}\qquad.../\sqrt[3]{...}$
$\sqrt[3]{1.3077}=1+r$
$r=\sqrt[3]{1.3077}-1\approx 0.0935$
$ r\approx 9.35\%$
