Consider the following problem with 5 activities A1, A2, A3, A4, A5.


Activity A1 can be started immediately and take 2 days to complete.

Activity A2 depends on A1, and takes 2 days to complete.

Activity A3 depends on A2, and takes 2 days to complete.

Activity A4 depends on A3, and takes 2 days to complete.

Activity A5 depends on A4, and takes 2 days to complete.


Moreover, at the end of activity A4, there is 20% chance that we will have redo activity A3. Assume that this rework can happen only once.


Required:

What is the probability of completing the project in 10 or fewer days?