Given the optimistic estimate (t.), most likely estimate (tm), and pessimistic estimate (t) in Table 4 based on the positively skewed beta probability distribution in PERT (Project Evaluation & Review Technique). (a Calculate: i. Expected activity duration (t.) (4 marks, C3) ji. Standard deviation (s) of the expected duration. (4 marks, C3) Variance (se) of the expected duration. (4 marks, C3) (b) The critical path is A-C-E-G = 21 days (refer to Appendix A1 and A2 - Areas under the standard normal curve) i. Compute the probability the project will be done in 23 days. (4 marks, C3) ii. Compute the probability the project will be done in 20 days. (4 marks, C3) Table 4 - Time Chart Activity Predecessors to tm to te Oe (o)? A none 1 4 7 B none 2 2 2 C A 2 5 8 D 3 4 5 E C,B 4 6 8 F . 0 0 6 G DE 3 6 9 (Note: Student are required to copy Table 4 in the answer booklet)