Answer
$\$654.98.$
Work Step by Step
According to the Formula for compounding continuously, where $P$ is the principal, the amount deposited, $r$ is the annual interest rate, $t$ is the number of years, $A$ is the amount you get back after $t$ years:
$A=P\cdot e^{r\cdot t}.$
Here we have:
$t=2.5\text{ years}$
$r=8\%=0.08$
$A=\$800$
Substitute these values into the formula above to obtain:
$\$800=P\cdot e^{0.08\cdot 2.25}$, hence $P=\frac{800}{ e^{0.08\cdot 2.25}}=\$654.98.$
