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# PMP Practice Questions #112

You are overseeing the development of a new educational platform and are in the process of scheduling key tasks. You have two critical tasks ahead and their three-point estimates are as follows:

Task A – Design of User Interface:

• Optimistic time (O): 20 days
• Most likely time (M): 35 days
• Pessimistic time (P): 50 days

Task B – Development of Content Management System (CMS):

• Optimistic time (O): 40 days
• Most likely time (M): 70 days
• Pessimistic time (P): 130 days

Using PERT technique, determine which task is more predictable (i.e., has lower uncertainty in its duration).

A) Task A is more predictable because it has a lower standard deviation.
B) Task B is more predictable because it has a lower standard deviation.
C) Both tasks are equally predictable as they have the same standard deviation.
D) Predictability cannot be determined from the standard deviation alone.

## Analysis:

The scenario presents a challenge in project scheduling, focusing on the predictability of two critical tasks within the development of an educational platform. The PERT (Program Evaluation and Review Technique) is employed to navigate this complexity, utilizing three-point estimates to evaluate the variability and thereby the predictability of each task’s duration. This analysis hinges on understanding the dispersion of estimates through standard deviation calculations, offering a structured means to assess and quantify the variability in task durations through optimistic, most likely, and pessimistic estimates. This analytical approach not only aids in forecasting durations but also in identifying which tasks exhibit higher predictability based on their estimated time frames.

Standard Deviation Calculation:

The connection between the initial analysis and the calculation of standard deviation lies in the PERT technique’s ability to quantify uncertainty. The standard deviation, a measure of uncertainty or variability, is calculated for each task using the formula: (PessimisticOptimistic)/6. This formula yields the standard deviation by dividing the range of estimates by six, offering a quantifiable measure of each task’s predictability.

• For Task A, the standard deviation calculation is (50−20)/6=5(50−20)/6=5, indicating a lower level of uncertainty.
• For Task B, it’s (130−40)/6=15(130−40)/6=15, which points to a higher level of uncertainty.

## Analysis of Options:

Option A: Task A is more predictable because it has a lower standard deviation. This option is supported by the standard deviation calculations. Task A’s lower standard deviation of 5 days, as compared to Task B’s 15 days, directly indicates less variability in its duration estimates, making it more predictable.

Option B: Task B is more predictable because it has a lower standard deviation. This statement is incorrect based on the calculated standard deviations. Task B, with a higher standard deviation of 15 days, exhibits more uncertainty than Task A, contradicting the premise of this option.

Option C: Both tasks are equally predictable as they have the same standard deviation. This option is also incorrect. The calculated standard deviations for Task A (5 days) and Task B (15 days) are different, indicating varying levels of predictability between the two tasks.

Option D: Predictability cannot be determined from the standard deviation alone. While standard deviation is a crucial measure of variability and hence predictability, this option suggests a broader view. However, within the context of this question and the application of the PERT technique, the standard deviation provides a clear basis for assessing task predictability, making this option less relevant.

Conclusion: The correct option is A) Task A is more predictable because it has a lower standard deviation. This conclusion is derived from the application of the PERT technique and the subsequent calculation of standard deviations for both tasks. The lower standard deviation for Task A signifies less variability in its duration estimates, making it more predictable compared to Task B. This analysis demonstrates the utility of the PERT technique and standard deviation calculations in project management, particularly in evaluating and comparing the predictability of different tasks within a project.

## Topics Covered

• Three Point Estimation
• PERT Technique
• Quantitative Risk Analysis
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