A Barbershop serves one customer at a time and provides three seats for waiting customers. If the plac ei sfull, customers go elsewhere. Arrivals occur according to a poisson distrubiton with a mean of 4 per hour. The time to get a haircut is exponential with a mean 15 minutes. Determine the following

a) The steady state probabilities
b) The expected number of customers in the shop.
c) The probability that customers will go elsewhere because the shop is full. Use queuing theory equations