How many dial-up input-output (I/O) ports are needed for a computer center to support 40 users with a blocking probability limit of 5%? Assume each user averages four calls per day with an average session duration of 30 min. If three users remain connected all day, what is the grade of service for the remaining 37 users? wax thinke in

I need precise solution , according to the book the answers are (a) 15 ports (14 ports with finite source analysis) (b) B= 9%