late event times
To perform the backward pass you will start with the last activity in the network an continue until you have reached the first activity in the network.
The first step in the backward pass is to copy the Early Event Time at the end of d:J last activity on the project into the Late Event Time at the end of the last activity. When the Early Event Time and the Late Event Time for the last activity in the project are the same. we can assume that the project needs to be completed as soon as possible.
Once the Late Event Time at the end of the last activity on the network has been 5el the backward pass is a simple application of subtraction. The Late Event Time at the start an Activity is equal to the Late Event Time at the end of the activity minus the duration of the activity. As with the forward pass calculation, the exception to this rule occurs where more than one activity start at the same node. The figure below shows an example of this situation.
