Project Schedule - Sample Exam Question - Desperate, need help!!

W

Wendy

All I am giving a class hand out to a group of PM's and I am needing the
answer to this question. greatly appreciate the answer and how you solved it.

A project manager has been asked by the client to meet the promise date of
the project. The PM analyzes the schedule before promising a date to the
client. The PM uses the program evaluation and reviwe technique to evaluate
the project schedule. She decides that based on the results of the PERT
calculation she can promise a delivery date of June 30. The expected value of
the project completion date is May 30. If the project manager is willing to
accept a 5% probability that the project will be delivered later than June
30, what is the standard deviation of the durations of the activities on the
critical path, Assume a five day work week. We are all stumped here on how to
calculate. Thanks in advance who all respond :)
 
J

JackD

It would appear that the standard deviation is about 10 days (since it does
not specify which year it is it is impossible to accurately convert the 30
calendar days into working days).

The reason is that for PERT it is assumed that the distribution follows a
normal curve. Therefore expected value has a probability of 50%, expected
value + 1 standard deviation = 68% probability and expected value + 2
standard deviations = 95%. So in this example 30 calendar days = 2 standard
deviations.
15 calendar days = 1 sd = 5/7*15 work days.

Of course this answer is wrong because the distribution does not typically
follow a normal curve, but the problem does not give enough information to
figure that out, so I assume it is meant to drill in the approximate answer.
 

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