A note on computing the exact probability distribution of the project completion time in a stochastic PERT network

In this paper a recursive method of determining the exact probability distribution of the project completion time in stochastic PERT networks is presented. It is assumed that durations of particular tasks are independent random variables with known distributions. The method concerns any network and can be applied in the case of any continuous distributions of task durations. Examples of exact density functions of project completion time for some networks are given. A comparison with the straightforward method is also included.