According to a Gallup Poll, the extent to which employees are engaged with their workplace varies from

Question:

According to a Gallup Poll, the extent to which employees are engaged with their workplace varies from country to country. Gallup reports that the percentage of U.S. workers engaged with their workplace is more than twice as high as the percentage of German workers. The study also shows that having more engaged workers leads to increased innovation, productivity, and profitability, as well as reduced employee turnover. The results of the poll are summarized in the following table:

If an employee is selected at random, what is the probability that he or she
a. is engaged with his or her workplace?
b. is a U.S. worker?
c. is engaged with his or her workplace or is a U.S. worker?
d. Explain the difference in the results in (b) and (c).