A PERT/CPM activity has an optimistic time estimate of 3 days, a most likely time estimate of 8 days, and a pessimistic time estimate of 10 days. The standard deviation of this activity is:
A) 7/9
B) 7/6
C) 1/3
D) 2/3

Question

Quizplus · Accepted Answer

The formula to calculate standard deviation for PERT/CPM is: (Pessimistic time estimate - Optimistic time estimate) / 6. 
Using the values given, we get: (10-3)/6 = 7/6. Thus, the standard deviation is 7/6.

A PERT/CPM Activity Has an Optimistic Time Estimate of 3