A poll revealed that the oil spill in the Gulf of Mexico in 2012 has made people in different countries more aware about en- vironmental damage as well as about dependency on using oil as a fuel source. Two-third of the adult population of America (67%), and a little more than half (52%) of the adult population of Eu- rope are aware of the spill. Assume that the following data was gathered.

a. Give an example of a simple event.

b. Give an example of a joint event.

c. Find the complement of the set of respondents who are from Europe.

d. Why is the set of respondents who are unaware and are from Europe a joint event?