Triangular Distribution

This distribution is very important in the case of phenomenon where testing is very expensive. An example is when you select the size of an underground reservoir, and three tests are usually per­formed to obtain the minimum, the maximum, and most likely. This distribution is used in schedule planning (discussed in Chapter 4). It estimates the time required to complete the activity by consider­ing three values: a minimum time, maximum time, and the most likely time to finish that activity.

In addition, it is also used to determine the estimated cost of a project where the maximum allowable value is about a 10-15% increase on the cost and the calculated minimum value is a 10-15% decrease for the calculated cost.

Triangular distribution is shown in Figure (3.17) where XJ7 X2, and Xm are the minimum, maximum, and most likely values, respectively.

Equation:

(X2 — *1 ) (X2 ~ *1*2 + *12 ) ‘~ XmX2 {X2~X, n)- XlXm {Xm ~ *1 )

18(x2-xl)

(3.36)