WARM-UP: Create a graph for the following information.
Prerequisite (Edges)
Task (Vertices)
Time
START 0 ­­­­­­­ A 3 NONE B 7 A C 6
A D 1 B,C E 3 C F 3 D,E FINISH QUESTIONS:
*What does it mean to finish the project?
*How long should this project take to finish?
HW 4.1 QUESTIONS: p172 #1-4, 7 (skip 5)
4.2 ­ Critical Paths
Of course, as the U.S. Government, how long would they want it to
take to construct one of these?
*EFFICIENCY!!!
So, they came up with a technique called PERT (Program
Evaluation and Review Technique) that allows them to find the
earliest completion of the project.
Finding this path of targeted tasks from the start and the finish
is called the critical path.
So, how do we go about finding a systematic way to identifying the
critical path for this project?
*We must find an earliest-start time (EST) for each task. This
number represents the earliest an activity can begin. What do you
think this is based on?
*All of its prerequisite tasks are completed!!!
To calculate the EST for each task:
1) Begin at the start.
2) Label each vertex with the smallest possible time that is
needed before the task can begin. (You must wait till all pre-req.
tasks are completed!!!)
3) Once all vertices are labeled, look for the critical path (HINT:
It should be the LONGEST path from start to finish - the
Highest start dates!)
Doing example from before on board...
Let's do an example off your HW - pg 177 #1
Find: 1) EST of each vertex 2) Critical Path 3) Min Project Time
QUESTION: If you are looking to cut the minimum project time,
what times should we look to decrease?
QUESTION: If a task is not on the critical path, do we have to
start that task as soon as the prerequisite task is finished?
The latest a task can begin without delaying the project's minimum
completion time is known as the latest-start time (LST) .
Turn in by the end of the period:
Find the EST, LST, and the critical path. Also answer the question
below.
QUESTION: What do you notice about the EST and LST of tasks
on the critical path?
HW: HW 4.2: p177 #1-5, 7-10
SMART Document Camera
Ensure that a SMART Document Camera is connected and isn't in use in an
other application.