What motivates employees? The Great Place to Work Institute evaluated nonfinancial factors both globally and in the United States. The results, which indicate the importance rating of each factor, are stored in Motivation.

a. At the 0.05 level of significance, is there evidence of a difference in the mean rating between global and U. S. employees?

b. What assumption is necessary about the population distribution in order to perform this test?

c. Use a graphical method to evaluate the validity of the assumption in (b).