hypothesis testing problem to two random samples from two different populations to determine whether the population means, or proportions are equal. Some examples for these types of cases are as follows;

• Is there any difference for the mean number of defective products which are manufactured by two different machine operators?

• Is there any difference of the mean age of customers who are choosing different colours of the same car model?

• Is there any difference between the mean exam grade of statistics course taken by economics and management department students?

• Is there any difference for the proportion of the student grades which are using two different reference books for the same of course?

• Is there any difference for the mean income level of the customers of two different banks?