7.10 A cyber cafe has six PCs that customers can use for Internet access. These customers arrive according to a Poisson process with an average rate of six per hour. Customers who arrive when all six PCs are being used are blocked and have to go elsewhere for their Internet access. The time that a customer spends using a PC is exponentially distributed with a mean of 8 min.

a. What is the fraction of arriving customers that are blocked?

b. What is the actual arrival rate of customers at the cafe?

c. What fraction of arriving customers would be blocked if one of the PCs is out of service for a very long time?