Operational research help!!!

Hi everyone

Am a bit stuck on a past examination question. Can you please help me:

2. An insurance company handles customer claims by processing the phone calls. Onaverage, there are 5 minutes between the calls, and these interarrival times areexponentially distributed. Several agents are assigned to processes the claims, eachagent has one telephone line and on average processes 8 claims per hour; theprocessing times are assumed to be exponential. If all agents are busy when atelephone call arrives, the customer is put on hold and periodically receives a recordedmessage that the call is important to the company and an agent will become availableshortly.(i) Verify that the probability that exactly one call arrives during a 5 minute periodis equal to the probability that no calls arrive during this period.[3 marks](ii) Determine the probability that during a 6 minute period more than two customersarrive.[3 marks](iii) Explain why it is not possible that all calls are handled by one agent.[2 marks](iv) The management of the company has set a guideline that a customer should notwait more than 90 seconds before an agent becomes available. Present yourworking that determines the smallest number of agents that are needed to satisfythis requirement.

[17 marks]

That is the question posted above. Please someone help me coz my exam is on Wednesday.

Kind REgards