Pallets arrive at a distribution center every $20$ seconds on average with a CV of $0\mathrm{.}5$ for

interarrival times. A single$-$pallet capacity pallet truck transports them to the entrance of the narrow$-$

aisle pallet rack storage area using a single command cycle. There are $8$ pallet trucks. For a pallet truck,

its average round$-$trip travel time is $2$ minutes with a CV of $0\mathrm{.}25$; its average pick$-$up time is $0\mathrm{.}1$ minutes

with a CV of $0\mathrm{.}1,$ and its drop$-$off time is also $0\mathrm{.}1$ minutes with a CV of $0\mathrm{.}1.$ A narrow$-$aisle lift truck stores

the pallets in pallet racks. For a lift truck, its average pick$-$up time is $0\mathrm{.}1$ with a CV $0\mathrm{.}2$; its average store

time is $0\mathrm{.}2$ with CV $0\mathrm{.}1,$ and its average round$-$trip travel time is $1\mathrm{.}5$ minutes with a CV $0\mathrm{.}55.$ A lift truck

handles one pallet at a time. There are $6$ lift trucks. Assume that there are no failures or interrupti