1 For example, the disorder sickle cell anaemia is caused by a mutation in the gene that instructs the building of a protein called haemoglobin. 2  This causes the red blood cells to become an abnormal, rigid, sickle shape. 3  However, in African populations, having this mutation also protects against malaria.
Optimistic time - generally the shortest time in which the activity can be completed. It is common practice to specify optimistic times to be three standard deviations from the mean so that there is approximately a 1% chance that the activity will be completed within the optimistic time.
However, if the network diagram has more than one critical path, you will be in a difficult situation. In this case, you will have to manage more than one path in parallel. As we know, the critical path has the longest duration, and its duration is known as the duration of the project. Since activities on a critical path have no float or slack, no activity should be delayed. If this happens, the project will be delayed.