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.
Late finish (LF) of an activity is the. earliest of the late start times of all successor activities. Late start. (LS) of an activity is its late finish less its duration. 12. The critical path is the shortest time possible for the comple-. tion of a series of activities, but that shortest time is the longest.