I'm embarrassed that I apparently remember nothing about statistics, but I'm hoping this is a pretty simple problem:

I'm trying to simulate the arrival of people in a queue using an exponential distribution function. To sample from the PDF, I do:

x = -ln(u) * v

Where u is a uniform random variable in [0, 1) and v is a scaling factor so that E[X] = v. This gives me the expected period between people. Unfortunately, what I want is to sample expected *frequency*.

Any tips would be really useful. Or maybe I'll just go dig up my old stats books...

Thanks!