Twenty$-$four customers arrive every hour $($Poisson distributed$)$ at Andy Johnson$$s food truck

when it parks outside the Colfax courthouse from $11$:$002$:$00$ on weekdays. It takes Andy a

mean time of $2$ minutes to fill each order $($exponentially distributed$).$

$($a$)$ What is the average waiting time $($in minutes$)?$

$($b$)$ If Andy$$s wife joins as a second server with the same processing time $($still one line$),$

what is the new average waiting time $($in minutes$)?$

$($c$)$ If instead Andy$$s wife uses her own truck and customers would be evenly split between

the two trucks, what would be the average waiting time $($in minutes$)?$