Answer
$1.628 \%$
Work Step by Step
Let the initial investment be $P = 850$, and the final value be $F=1000 $. We know that
$$
\begin{aligned}
F& =P\left( 1+\frac{r}{n}\right)^{nt} \\
\end{aligned}
$$
where $n= 4$ and $t= 10$ for this problem. It follows that
$$
\begin{aligned}
850\left( 1+\frac{r}{4}\right)^{40}& =1000\\
\left( 1+\frac{r}{4}\right)^{40}& =\frac{1000}{850}\\
1+\frac{r}{4}& = \left(\frac{100}{85}\right)^{\frac{1}{40}}\\
r&= 4\left(\frac{100}{85}\right)^{\frac{1}{40}}-4\\
r&= 0.01628=1.628\%\\
\end{aligned}
$$
The nominal interest rate is $1.628 \%$.
