We looked at probability distributions and how the techniques we have developed can be used to compute probabilities. In particular we look at computing a 'weighted area' in the plane with the 'weighting' given by a distribution function. We studied an example of two independent queues. This example brings together most of the techniques studied on this course, with the key part being to translate the problem into a double integral to be computed and to correctly identify and describe the region of integration (a Type I triangle in this case). The other steps are procedural but still challenging technically.