# problem in negative negative exponential distribution

#### yog782004

Hi I have problem in below mention question can any body help me how I can solve

Ships arrive at a port at a rate of one in every 3 hours, with a negative exponential distribution of inter arrival times. The time a ship occupies a berth for unloading and loading has a negative exponential distribution with an average of 12 hours. If the average delay of ships waiting for berths is to be kept below 6 hours, how many berths should there be at the port

#### mr fantastic

MHF Hall of Fame
Hi I have problem in below mention question can any body help me how I can solve

Ships arrive at a port at a rate of one in every 3 hours, with a negative exponential distribution of inter arrival times. The time a ship occupies a berth for unloading and loading has a negative exponential distribution with an average of 12 hours. If the average delay of ships waiting for berths is to be kept below 6 hours, how many berths should there be at the port
Truly amazing what Google turns up .... See example 6 here: http://www.websukat.com/SMU-Books/Operations-Research/8-Infinite-Queuing-Models.pdf

#### blogu

I had gone on that link after, that itself I realized its not properly given and I am not able to understand it, so, I posted this thread about the question hoping to get correct answer (Doh)