If a principal of $P$ dollars is deposited in an account earning interest at the rate of $r /$ year compounded continuously, then the accumulated amount at the end of $t$ years is given by $$A=f(P, r, t)=P e^{r t}$$
dollars. Find the accumulated amount at the end of 3 years if a sum of $\ 10,000$ is deposited in an account earning interest at the rate of $6 \% /$ year.