Answer
$ r\approx 6.3\%$
Work Step by Step
The present value $P$ of $A$ dollars to be received after $t$ years,
assuming a per annum interest rate $r$ compounded $n$ times per year, is $P=A\displaystyle \cdot\left(1+\frac{r}{n}\right)^{-nt}$
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$A={{\$}} 25,000, P=15,334.65$
$n=1, \mathrm{t}=8.$
$r=?$
$15,334.65=25,000(1+\displaystyle \frac{r}{1})^{-8}\qquad.../\div 25,000$
$\displaystyle \frac{15,334.65}{25,000}=(1+r)^{-8}\qquad.../(....)^{-1/8}$
$\displaystyle \left(\frac{15,334.65}{25,000}\right)^{-1/8}=1+r$
$r=\displaystyle \left(\frac{15,334.65}{25,000}\right)^{-1/8}-1\approx 0.63$
$ r\approx 6.3\%$
