A project manager made 3-point estimates on a critical path and found the following results:

Need help is calculating the below problem, found in one of the mock test. Pls. help

Optimistic Most Likely Pessimistic PERT Weighted Avg

Act. A 12 15 24 16

Act B 8 9 14 9.7

Act. C 15 19 27 19.7

Act. D 10 14 28 15.7

Act. E 17 20 35 22

estimate for the critical path: 83.1

Assuming ±3 sigma precision level for each estimate, what is the standard deviation of the allover path?

1. App. 4.2 days

2. App. 5.2 days

3. App. 6.2 days

4. You can not derive the path standard deviation from the information given.