The human resources director is studying the age of employees at two different plants (A and B). Random samples of employees are taken from both plants and the ages of the employees are recorded, resulting in the following summary statistics:

Plant A: XX_A = 44, _A= 6, n_A= 30

Plant B: XB=41,BXB=41,B= 4, n_B= 20

The director wants to test to see if there is a difference in the average ages of the employees at the two plants. What is the test statistic for this two sample hypothesis test of means? Calculate the difference as A-B.