Given the CPM/PERT project network segment the latest finish (LF) times for activity 3 is

To answer your question, I would need more specific information about the project network segment. The latest finish (LF) time for an activity in a CPM/PERT chart is determined by working backwards from the project end date and considering the duration and dependencies of each task.

Here are the steps to calculate the LF:

1. Identify the project's end date or the latest finish time of the project. This is the LF for the final activity.

2. For each activity leading up to the final activity, subtract its duration from the LF of the activity that immediately follows it. This will give you the LF for that activity.

3. If an activity has more than one dependent activity, use the smallest LF among these dependent activities for calculation.

4. Repeat this process for all activities in the project.

Without specific information about the durations of the activities and their dependencies, it's impossible to provide the LF for activity 3.