I've added a example for reference...

A contractor has carefully reviewed the plans and specifications for the construction of a small warehouse, identified for the following activities during her work breakdown analysis, and estimated the duration for each activity: Predecessor(s) Act A B D Duration 3 7 6 3 A A E Description Site clearing Removal of trees General excavation Grading general area Excavation for utility trenches Placing formwork and reinforcement for concrete Installing sewer lines Installing other utilities Pouring concrete 2 B, C F 4 G H I 3 4 1 B, C DE DE F, G Based on the information above, complete a CPM calculation and answer the following questions. 1. Draw an AON network diagram schedule for this project (2.1 points). Note: You must put start and finish nodes at the beginning and the end of your network, respectively. 2. Calculate the ES, EF, LS, LF, TF, and FF and complete the table below (5.4 points) Note: The start and finish nodes must be calculated during the CPM calculation. Their durations must be zero. ES EF LS LF TF FF Activity A B D E F G H I Note: Each cell will be graded with a 0.1 point. 3. Calculate the total project duration in work days (1 point) 4. Identify the critical path(s). (1.5 points) 033 8 4 12 3 5 8 B 3 0 8 11 3 15 15 4 19 G 15 O 19 003 347 D 4 1 8 8715 E E 8 0 15 Duration Early start (ES) Early finish (EF) 50% 5 5 10 F Activity F Late start (LS) Late finish (LF) 10 5 15 Total float