Q$3.$ A two$-$server operation with two service windows and two employees $($one employee per window$).$ The

employee stationed at each window fills the order and takes the money from the customer. The average service

time for this alternative is also $1\mathrm{.}5$ minutes for each server. This service operation assumes that although the two

service windows are located at the opposite sides of the restaurant building, there would be only one common

lane leading to the building from the parking lot, i$.$e$.,$ the arriving customers would follow the same, common,

lane and only at the very end they would move to the first window available $($on the left or on the right side of

the building$).$