TOPIC: Q: about Beta & Triangular

Could someone please help me ...
How do we know when to use these formulas:
a) Beta = (Pessimistic + (4 * Most Likely) + Optimistic) / 6
b) Triangular = (Pessimistic + Most Likely + Optimistic) / 3
I know that the first formula (a) used for weighted average, but how can we recognize if the given information in the question is for weighted average?
Thanks.

In case the estimates were made with no real experience and are more best guesses use the triangular. But when there is already experience from similar previous projects or experts are doing the estimates you should use the beta distribution . Is there such information in the question about the "quality" of the estimates?

I know this may seem vague, but on the exam it will be readily apparent as to which formula to use. You should be fine!
-Steven

Hi Steven,

If the question does not give any hint or if nothing other than the values of P,M,O are specified, then by default, do we use PERT or do we use Triangular?

Well, I got both results as answers in both questions that I had.
During my preparation it was only one correct answer from either one of the two. while on the actual exam, both results appeared so who knows if I got it right...

Did you get the answer for that? That's what I got twice on the exam.
I used the regular one and who knows if I got it right.

I am also confused about how to know when to use which version. In taking the post-test quiz for Lesson 6, Question 8 gives both the triangular and Beta answers as options. I went with triangular because it didn't indicate to me that a weighted average was required. Am I supposed to assume, as someone said before, that because there is a "policy" and previous observations regarding the time required, that a beta distribution is more appropriate? Would a triangular distribution only be appropriate if the question basically said, "we've never done this before and are taking a wild stab in the dark?"