What is the Probability of Each Customer Getting a DVD in a Rental System?

[kannadasan]

We are involved in web development and we are implementing a new project named "DVD rental". The problem we face was to finding a solution for giving a priority for the customer.
It is described as,
There are certain amount of DVD in the stock(222), the demand fot that DVD is 300, so we are lagging 78 DVD's. Now the 78 people are waiting in queue to get the DVD when rented DVD returned.Here the waiting members will not be defined priorly. But we have to give the priority for each of the customer.
How to find the probability of getting the DVD by every people.

S.Kannadasn

 

[HallsofIvy]

I don't understand what you are asking. In the titel you talk about "probability", but then you ask about a "priority" and then, again, ask about a "probability". What exactly do you want to do?

 

[EnumaElish]

Yes, the question is not clear. Why isn't the answer "each of the 78 people in the queue will get the DVD with certainty (probability = 1 or 100%), if they are willing to wait long enough (which can be a very long time)"? Is the question, "what is the probability that each of the 78 people will get the DVD within X number of days"?