We shall assume that all the observations have a normal distribution, and the variance is the same at both locations in the mine, even though the means may be different. In this example, the sample size are … and … , and the value of the statistic … defined by Eq. (8.6.3) is 3.442. Also, by the use of a table of the … distribution with 16 degrees of freedom, it is found that … , so that the tail area corresponding to this observed value of … is less than … Hence, the null hypothesis will be rejected for any specified level of significance … (In fact, the two – sided tail area associated with …)