Beta Distribution (BER [:1 In triangular distribution each estimate is given equal weightage, added to each other and then divided by three. However, in beta distribution which is also known as PERT (Program Evaluation and Review Technique), the most likely estimate is given more weightage, i.e. four times. Afterwards all estimates are added and divided by six. Expected Duration (Beta Distribution) te= (to + 4tm + tp)/6 Standard Deviation and Variance Standard deviation is the amount of variation in a data set. It is the measure of how the numbers are spread. A low standard deviation means that data points are close to the mean of the set, and a high standard deviation means that the data points are spread out over a wider range. Standard Deviation (SD) = (tp to)/6 Variance is the square of the standard deviation. Variance = (SDJI2 Exam pie: For any activity you estimate that it can be completed within 10 days. If the weather conditions are bad, this activity can take about 11 days. However, if all conditions are favorable, this activity can be completed in 7 days. Using PERT, calculate the three point estimate, standard deviation, and variance for this activity. Solution: We know the PERT estimate formula: te= (to + 4tm + tp)/6 Here: te = PERT Estimate: to be calculated to = Optimistic Time = 7 days tm = Most Likely Time = 10 days tp = Pessimistic Time = 11 days Substituting these values in the PERT formula: te= (to + 4tm + tp}/6 : (7 +4*10 + 11)/6 : (7+40+11)/6 = 58/6 : 9.6 days. Hence the PERT estimate for this activity is 9.6 days. Standard Deviation = (tp to)/6 : (11 71/6 = 4/6 = 0.67 N ow, Variance = (Standard Deviation)2 = 0.67*0.67 = 0.45 *** Practice uestion: 2 You have been given a task which may take 60 days to complete; however if the conditions are favorable it may be completed in 55 days. In the worst case scenario, it may take 70 days. Find the PERT estimate, standard deviation and variance for this task