Exercise problems Questions 25, 26, 27 \& 28 - Just refer to the tables - Draw an AON diagram - Find ES, EF, LS, LF - Find critical Paths and activities 23. Refer to Table 5-4 and Figure 5-14. Recalculate the variance for each activity on the assumption that the optimistic and pessimistic estimates were made with a 95 percent probability. Recalculate the probability that the critical path will be completed in 50 days. 24. Refer to Table 5-4 and Figure 5-14. Recalculate the variance for each activity on the assumption that the optimistic and pessimistic estimates were made with a 90 percent probability. Again, recalculate the likelihood that the critical path will be finished in 50 days. 25. Given the information in the following table: a. Construct the network diagram. b. Find each activity's ES, EF, LS, and LF. c. Identify all paths. Which path is the critical path? d. Calculate the slack for each activity. e. How long will it take to complete the project? 26. Given the information in the following table, draw the AOA network. Using the same information, enter the data into MSP assuming a seven-day workweek. (To change the calendar in MSP from its frve-day week default click "Help," type "calendar change," and follow directions.) Develop the appropriate AON network and Gantt chart. Using any method you wish, find the critical path and critical time for the network. Then find the slack for all activities. 27. In the following table, task durations are given in weeks. The estimates were made at the 95 percent level (see Section 5.2, Calculating Probabilistic Activity Times subsection). a. Find the expected time and variance for each task. b. Draw the network (either AOA or AON ) and find the critical path and time. c. Find the probability that the critical path will be completed in 23 weeks. d. Find the probability that the other main paths will be completed in 23 weeks. e. What is the probability that the entire network will be completed in 23 weeks? 28. Enter the following information into an Excel 2 spreadsheet. The time estimates were made at the 90 percent level (see Section 5.2, Calculating Probabilistic Activity Times subsection). All activity times are in days. a. Draw the network. (You may use MSP, or draw an AOA or AON network by hand.) b. Using Excel 5, calculate the expected time (TE) and variance for each activity. c. Using the expected times, find the critical path and critical time. (Use the analytic method.) d. Find the probability that the critical path will be completed in 38 days or less