The Waterfall Buffet in the lower level of the National ArtGallery serves food cafeteria-style daily to visitors andemployees. The buffet is self-service. From 7:00 A.M. to9:00 A.M. customers arrive at the buffet at a rate of eight perminute; from 9:00 A.M. to noon, at four per minute; from noon to 2:00, at 14 per minute; and from 2:00 P.M. to clos-ing at 5:00 P.M., at eight per minute (Poisson distributed). All the customers take about the same amount of time to serve themselves and proceed to the buffet. Once a cus-tomer goes through the buffet, it takes an average of 0.4 minute (exponentially distributed) to pay the cashier.The gallery does not want a customer to have to wait longerthan four minutes to pay. How many cashiers should beworking at each of the four times during the day?

The Waterfall Buffet in the lower level of the National Art
Gallery serves food cafeteria-style daily to visitors and
employees. The buffet is self-service. From 7:00 A.M. to
9:00 A.M. customers arrive at the buffet at a rate of eight per
minute; from 9:00 A.M. to noon, at four per minute; from

noon to 2:00, at 14 per minute; and from 2:00 P.M. to clos-
ing at 5:00 P.M., at eight per minute (Poisson distributed).

All the customers take about the same amount of time to

serve themselves and proceed to the buffet. Once a cus-
tomer goes through the buffet, it takes an average of

0.4 minute (exponentially distributed) to pay the cashier.
The gallery does not want a customer to have to wait longer
than four minutes to pay. How many cashiers should be
working at each of the four times during the day?