Polydispersity effect and universality of finite-size scaling function

We derive an equation for the existence probability E-p for general percola tion problem using an analytical argument based on exponential-decay behavi our of spatial correlation function. It is shown that the finite-size scali ng function is well approximated by the error function. The present argumen t explain why it is universal. We use Monte Carlo simulation to calculate E -p for polydisperse continuum percolation and find that mono- and polydispe rse system have the same finite-size scaling function.