I was wrong about what the rand(N) function did in ruby

I assumed that rand(N) would find a floating point number from 0 up to N. But in fact it would find an integer from 0 up to N. So I changed this to the corresponding code for julia.
Code for displaying results using Winston

Requires Windston installed with Pkg.add("Winston"). You have to load julia first and then you can do e.g. include("graphs.jl") to display the graph.

Looking at the results now, it does not seem right because there is a very clear linear relationship, but I am expecting queue lengths to increase rapidly as population increases while in the beginning there should be little queue even as population grows.