I only need answer for C

Consider the following network diagram A E B Below are the activity time estimates, in months. Activity Optimistic Most likely Pessimistic A 2 5 11 B 3 3 7 1 3 5 D 6 8 10 E 4 7 10 a. What is the expected duration of the activity A? 1.5 months 2.25 months 5 months 5.5 months O 6 months b. Refer to the network diagram in the previous question. What is the standard deviation of the duration of the path B-C-D? 01.15 months 1.33 months O 2 months 2.83 months Another value QUESTION 26 c. What is the probability that the path A-D will be completed within 15 months? 0.1804 0.7111 O 0.7556 0.82 O 0.9138