Project and operation management

Could you please do the calculations for the table in part c? I need help in understanding it.

Solution: (a) Calculate the missing expected times and standard deviations. (b) Find the critical path(s) and the expected project duration. 1. A-B-E-K: 9.5+3+6+2.5=21 2. A-B-F-G-J-K: 9.5+3+8+3+7+2.5=33 3. A-C-G-J-K: 9.5+12+3+7+2.5=34 4. A-D-H-I-J-K: 9.5+5.5+3+9+7+2.5=36.5 (critical path and expected project duration is 36.5 ) (c) What is the earliest start time for activity E ? What is the latest finish time for activity J