## College Algebra (10th Edition)

$r\approx 6.3\%$
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 $P=A\displaystyle \cdot\left(1+\frac{r}{n}\right)^{-nt}$ --- $A={{\$}} 25,000, P=15,334.65n=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+rr=\displaystyle \left(\frac{15,334.65}{25,000}\right)^{-1/8}-1\approx 0.63 r\approx 6.3\%\$