QUESTION $3$

A single automated checkout machine at a grocery store has an average time between Poisson arrivals of $12$ minutes. The machine processes customers at a constant rate of six per hour. What is the average time $($in minutes$)$ that an arriving customer will spend in the queue?

A$.0\mathrm{.}42$

B$.0\mathrm{.}84$

C$.50$

D$.25$

$10$ points