12/20/2023 0 Comments Statistical calculations pmpHere are the answers to the quiz questions: I hope with this explanation, you can answer most of the questions on the Activity Duration Estimate Quiz visually. Answers to Activity Duration Estimate Quiz And the probability of the project taking more than 60 days for completion is 0.1% (~ 100% - 50% - 34.1% - 13.6% - 2.1%). Similarly the probability of completing the project within 52 days is 84.1% (~ 50% + 34.1%). So, the probability of completing the project within 44 days is 15.9%. From the figure, we can tell that the area under the curve on the left side of the mean (μ) is 50% of the total area, and the area between -1σ and μ is 34.1%. We know that 44 days represents -1σ on the curve. Now if we want to know the probability of completing the project within say 44 days, all we need to do is to determine the area on the left side of 44 days on the curve. 99.7% probability that the project will complete between 36 to 60 days (three standard deviations of the mean).95.5% probability that the project will complete between 40 to 56 days (two standard deviations of the mean).68.2% probability that the project will complete between 44 to 52 days (one standard deviation of the mean). 50% probability that the project will complete within 48 days (mean).From what we have learned so far, there is: Let’s say the PERT estimate (mean) of the project is 48 days and the standard deviation is 4 days. Therefore, we can say that there’s 50% probability that the data points will fall below the mean, and another 50% probability for them to be above the mean. 50% of the area under the curve falls on the left side of the mean (below the mean) and the remaining 50% falls on the right (above the mean). The peak of the curve is the mean or central value of the distribution. For the normal distribution, we can determine the probability of the data points falling within any two points a and b on the curve by calculating the percentage area under the curve between those two points. The light, medium, and dark blue portions combined represent the area within three standard deviations of the mean (-3σ, +3σ). 99.7% probability that the data points will fall within three standard deviations of the mean.The medium and dark blue portions combined represent the area within two standard deviations of the mean (-2σ, +2σ). 95.5% probability that the data points will fall within two standard deviations of the mean.Interestingly, this area is 68.2% (~ 34.1% + 34.1%) of the total area under the curve. The dark blue portion represents the area within one standard deviation of the mean (-1σ, +1σ). 68.2% probability that the data points will fall within one standard deviation of the mean.Refer to the image above and you’ll get a better idea.įor the normal distribution, statistics say that there is: The normal distribution curve is a bell-shaped curve, and is symmetrical on both sides of the mean. PERT assumes that the expected duration of a project follows the normal distribution.
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