The Poisson, the negative exponential, and the rectangular distributions

Abstract

These involve events which occur at random, with a certain probability. For example, cosmic ray particles arrive at random (at least to a very good approximation); if we know that, on the average, 10 particles arrive in a minute, then the number that arrive in any given hour will not necessarily be 10 × 60 = 600. So the probability distribution of the arrival of other numbers, e.g. 610 or 579, is of considerable importance.