PERT and CPM MCQ Quiz in తెలుగు - Objective Question with Answer for PERT and CPM - ముఫ్త్ [PDF] డౌన్‌లోడ్ కరెన్

Explanation:

Critical activity:

Critical activities are those activities whose float is zero and they lie on the critical path.

Float:

Relax or delay provided to any activity is known as float.

Floats are of three types. They are as follows:

Total Float (TF):

The maximum delay or relax provided to any activity without affecting the project duration.

TF = L_j – E_i – d_ij

Free Float (FF):

Relax or delay provided to any activity without affecting the Earliest Start Time (EST) of the successor activity.

FF = E_j – E_i – d_ij

Independent Float:

Relax or delay provided to any activity without affecting the Earliest Start Time (EST) of successor activity as well as Latest Finish Time (LFT) of the predecessor activity.

IF = E_j – L_i - d_ij

Relation among float TF ≥ FF ≥ IF

Critical Path:

• The longest path in the network diagram is called Critical Path.
• The length of the Critical Path determines the minimum duration required for the completion of the project.

Concept:

This is a case of activity on node network system (AON).

Slack = latest finish time – Earliest finish time

Calculation:

Slack = latest finish time – Earliest finish time

Slack on Activity L = 42 – 40 = 2

Important Points:-

1. AON network system enables efficient scheduling and controlling.

2. AON network system eliminates the use of dummies thus logical relationship is established by using arrows.

PERT approach takes account of the uncertainties. In this approach, 3-time values are associated which each activity. So it is probabilistic.

Whereas CPM involves the critical path which is the largest path in the network from starting to ending event and defines the minimum time required to complete the project. So it is deterministic.

Explanation:

PERT is almost identical to the critical path method (CPM) technique except it assumes each activity duration has a range that follows a statistical distribution.

• In PERT the Normal distribution is used for the completion time of Project.
• PERT uses three-time estimates for each activity. Basically, this means each activity duration can range from an optimistic time to a pessimistic time, and a weighted avenge can be computed for each activity. 
• Because project activities usually represent work, and because work tends to stay behind once it gets behind, the PERT developers chose an approximation of the beta distribution to represent activity durations.
• The activity durations can be skewed more toward the high or low end of the data range. 

• Figure A depicts a beta distribution for activity duration that is skewed toward the right and is representative of work that tends to stay late once it is behind. 
• The distribution for the project duration is represented by a normal (symmetrical) distribution shown in Figure B. 
• The project distribution represents the sum of the weighted avenges of the activities on the critical path.

Confusion Points In PERT individual activities follows Beta distribution whereas whole project duration follows Normal distribution.

Explanation: 

Critical activity:

Critical activities are those activities whose float is zero and they lie on the critical path.

Float:

Relax or delay provided to any activity is known as float.

Floats are of three types. They are as follows:

Total Float (TF):

The maximum delay or relax provided to any activity without affecting the project duration.

TF = Lj – Ei – dij

Free Float (FF):

Relax or delay provided to any activity without affecting the Earliest Start Time (EST) of the successor activity.

FF = Ej – Ei – dij

Independent Float:

Relax or delay provided to any activity without affecting the Earliest Start Time (EST) of successor activity as well as Latest Finish Time (LFT) of the predecessor activity.

IF = Ej – Li - dij

Relation among float TF ≥ FF ≥ IF

Explanation:

According to the above network following inferences can be drawn:

1. Event 1 is the starting event and Event 8 is the end event.
2. Event 2 precedes Event 3 and Event 4 and follows Event 2.
3. Event 3 precedes Event 5, Event 6, and Event 7 and follows Event 2.
4. Event 4 precedes Event 7 and follows Event 2.
5. Event 5 follows event 3 and precedes Event 6.
6. Event 6 precedes Event 8 and follows Event 5, Event 3, and Event 7.
7. Event 7 precedes Event 6 and follows Event 4 and Event 3.

Note:

Option 1: Incorrect as

• Event 7 can occur only after both event 4 and event 3 are complete.

Option 4: Correct as

• Arrows coming out from Event 2 and ending towards Event 3 and Event 4 which means Event 3 and Event 4 occur after event 2.

Explanation:

Given,

From the Above data following network is obtained

As it is asked about Duration of Project It comes out to be 43 days

Concept:

CPM does not directly model uncertainty.

PERT was developed to address the needs of projects which are being done for the first time – a challenge to estimate activity duration.

PERT (Program Evaluation and Review Technique) uses 3 cases:

• Most Optimistic
• Most Pessimistic
• Most likely durations

PERT determines the probability for each duration, whereas CPM considers the most likely duration.

In the standard PERT analysis, the distribution assumed for the activity times is a Beta distribution.

CPM (Critical Path Method) is an activity-oriented method. CPM involves the concept of the critical path which is the largest path in the network from starting to ending event and defines the maximum time required to complete the project. It is a deterministic approach. Float along the critical path is Zero.

Float is given by LST – EST or LFT – EFT

Where

LST → Latest Start Time, EST → Early Start Time, LFT → Latest Finish Time, LST → Latest Start Time

For a critical path, LFT – EFT = 0

∴ Along the critical path Earliest finish time (EFT) = Latest finish time (LFT) 

Noncritical activity is the activity where enough float time is available.

Noncritical activity is the one where, EST

Earliest start time (EST):- is the time at which an activity can start, assuming all predecessors have been completed.

Earlies finish time (EFT):- Earliest time at which an activity can be finished.

Latest start time (LST):- Latest time at which an activity can start so as to not delay the completion time of the entire project.

Latest finish time (LFT):- Latest time by which activity has to finish so as to not delay the completion time of the entire project.