C H A P T E R
1. There are many possible answers. Project management is needed in large construction jobs, in implementing new information systems, in new product development/marketing, in creating a new assembly line, and so on. 2. Project organizations make sure existing programs continue to run smoothly while new projects are successfully completed. 3. The three phases involved in managing a large project are: planning, scheduling, and controlling. 4. PERT and CPM help answer questions relating to which task elements are on (or likely to be on) the critical path and to probable completion times for the overall project. Some specific questions include: When will the entire project be completed? Which are the critical activities or tasks in the project; that is, the activities that will delay the entire project if completed behind schedule? Which are the noncritical activities; that is, those that can run behind schedule without delaying the whole project? How far behind schedule can these activities run without disrupting the completion time? What is the probability that the project will be completed by a specific date? At any particular date, is the project on schedule, behind schedule, or ahead of schedule? On any given date, is the money spent equal to, less than, or greater than the budgeted amount? Are there enough resources available to finish the project on time? If the project is required to be finished in a shorter amount of time, what is the least-cost way to accomplish this? 5. WBS is a hierarchial subdivision of effort required to achieve an objective. It defines a project by breaking it down into manageable parts and even finer subdivisions. 6. A Gantt chart is a visual device that shows the duration of tasks in a project. It is a low cost means of ensuring that (1) all activities are planned for, (2) their order of performance is planned for, (3) the activity times are recorded, and (4) the overall project time is developed. 7. The difference between AOA and AON is that activities are shown on arrows in the former and on the node in the latter. We primarily use AON in this chapter.
8. Any late start or extension of an activity on the critical path will delay the completion of the project. 9. To crash an activity, the project manager would pay money to add resources (overtime, extra help). 10. Activity times used in PERT are assumed to be described by a Beta probability distribution. Given optimistic (a), pessimistic (b), and most likely (m), completion times, average or expected time is given by: t a 4m b 6
and the variance by:
Variance b 6 a
11. Early start (ES) of an activity is the latest of the early finish times of all its predecessors. Early finish (EF) is the early start of an activity plus its duration. Late finish (LF) of an activity is the earliest of the late start times of all successor activities. Late start (LS) of an activity is its late finish less its duration. 12. The critical path is the shortest time possible for the completion of a series of activities, but that shortest time is the longest path through the network. Only the longest path allows time for all activities in the series; any smaller amount will leave activities unfinished. 13. Dummy activities have no time duration. They are inserted into a AOA network to maintain the logic of the network, such as when two activities have exactly the same beginning and ending events. A dummy activity is inserted with one of them so that the computer software can handle the problem. 14. They are (1) Optimistic time estimate (a), an estimate of the minimum time an activity will require; (2) Most likely time estimate (m), an estimate of the normal time an activity will require; and (3) Pessimistic time estimate (b), an estimate of the maximum time an activity will require. 15. No. In networks, there is no possibility that crashing a noncritical task can reduce the project duration....
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