A contractor's project being analyzed by PERT has an estimated time for the critical path of 120 days. The sum of all activity variances is 81; the sum of variances along the critical path is 64. What is the probability that the project will take 130 or more days to complete?
A) 0.10565
B) 0.13350
C) 0.85120
D) 0.89435
E) 1.29

Question

Quizplus · Accepted Answer

The probability can be found using the Z-score formula: Z = (X - μ) / σ, where X is the desired time (130 days), μ is the expected time (120 days), and σ is the standard deviation (square root of the variance along the critical path, which is √64 = 8). So, Z = (130 - 120) / 8 = 1.25. Using the standard normal distribution table, the probability of Z being less than 1.25 is approximately 0.89435. Therefore, the probability of the project taking 130 or more days is 1 - 0.89435 = 0.10565.

A Contractor's Project Being Analyzed by PERT Has an Estimated