TOPIC: Is this PERT? PERT is determined using three points: Optimistic (O), Most Likely

Is this PERT? PERT is determined using three points: Optimistic (O), Most Likely (M), and Pessimistic (P).

Any help is welcomed.

A project has tight deadlines to meet. The project manager worked diligently with the regulatory body and the intermal stakeholders to define the minimum viable product (MVP). Due to insufficient historical data, the work package owner leveraged a three-point triangular estimate and came up with an expected duration of 125 days. The optimistic duration is 85 days and the pessimistic duration is 175 days.
The most likely duration is , I applied 128, 115 is correct
days.
(Enter the days rounded to the nearest whole number in numerical format. DO NOT include "days" in your response.)

Correct answer is 115, HOW

Thanks,
Bill

I had the same issue concerning a similar question in the past. The solution is to apply the following Three-Point Estimate equation:
Estimate = (Least + Most + Optimistic)/3
In your example, this gives: 125 = (175 + x + 85)/3
x therefore solves to 115.

Thanks so in this case . you would add, 175 + x + 85)/3 , which provides X , which = 86, then you plug in 86 at X so 175 + 86 + 85)/3, which gives you 115. Just trying to udnertand logic on how to discover solution.

Thanks,
Bill

Using this equation you need to isolate x, i.e. the 'most likely estimate', in order to find the answer that the question is looking for. There is of course more than one way to approach it, but from my school arithmetic (many, many moons ago ), I'd use the following:
- Multiply both sides of the equation by 3 (to remove the right side denominator 3)
- Isolate x on the right (by subtracting the total of 175 and 85 from both sides).

Thus, (125 * 3) - (175 + 85) = x = 115.

This method can therefore be used in any situation in which you are supplied the estimate of the Expected duration (125 days in this case) but only two of the three other estimates.

The PMI apparently likes to call this formula the Triangular Distribution. The use of the word 'triangular' in the question is likely intended to point candidates to this formula rather than the PERT formula.