A local bank has two drive$-$thru teller windows with an essentially unlimited queue length. They estimate that the arrival rate during their most busy time will average about $40$ cars per hour. They also estimate they can serve an average of $50$ cars per hour. Management wants to make sure that the system is operating efficiently. $($Assume arrivals follow the Poisson distribution and service times follow the exponential distribution.$)$

$$What is the probability that there will be no cars in the system?

Group of answer choices

$0\mathrm{.}4286$

$0\mathrm{.}0500$

$0\mathrm{.}9500$

$0\mathrm{.}4134$