Consider the frame of 52 full-time employees of Beta Technologies, Inc. Beta’s human resources manager has collected current annual salary figures and related data for these employees. The data are in the file P2_1.XLS.

a. Compute the mean, median, and standard deviation of the annual salaries for the 52 employees in the given frame. 

b. Assuming that the human resources manager wishes to stratify these employees by the number of years of post-secondary education, select such a stratified sample of size 15 with approximately proportional sample sizes.

c. Compute the mean, median, and standard deviation of the annual salaries for the 15 employees included in your stratified sample. Compare these statistics with your computed descriptive measures for the frame obtained in part a. Is your stratified sample representative of the frame with respect to the annual salary variable?