If we want to analyze a real system with a large number of input data, it is very convenient to determine a
probability distribution that best fits to given input data. There are many statistical methods to determine the correct
probability distribution and one of them is Chi-Square Goodness of Fit Test. This statistical test can be also used to find out
a probability distribution of time intervals between arrivals of customers at post office. Intervals between arrivals of
customers occur in continuous time and therefore we consider continuous probable distributions.
