Project Variance and Standard Deviation Project variance oo2 = SUM(variances of all critical path activities) Project standard deviation O = SQRT (Project variance) . Value: 2 A project has 3 critical path activities, of which the variances are 2, 3 and 4, respectively. Then, project variance will be and standard deviation will be Check Answer Probability of Project Completion . . Important question What is the probability of finishing the project within (or beyond) a certain amount of time? Assumptions Project duration is normally distributed Activity times are independent Normal distribution parameters = expected completion time o = project standard deviation Normal Probability Calculations Z = (Target - llo The target is Z standard deviations away from the expected