The following data concern an activity that has to be
performed as part of a project:
Expected duration (days) 10
Standard deviation of the duration 2
Expected labor-days 30
Standard deviation of labor-days 3
a. What is the probability that completing the activity on
time will require at least a 10%
addition to the expected labor-days?
b. A crew of three workers is assigned to this activity.
What is the probability that it will
be completed in fewer than 11 days?
State your assumptions for both parts.