Answer
$\$493.47$
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:
$t=3\text{ years}$
$r=7\%=0.07$
$P=\$400$
Substitute these values into the formula above to obtain:
$A=\$400\cdot e^{0.07\cdot 3}\approx\$493.47$
